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DISCUSSION Stan Hoeppner 2 participants 11 messages Oct 3, 2014 bcache (block layer cache)

lore
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lore
#0 lore raw
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

What's the problem here?

Thanks,
Stan

#1 lore raw

Please include any bcache messages printed in dmesg when this happens.

Quoted 21 lines · Stan Hoeppner
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

What's the problem here?

Thanks,
Stan
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#2 lore raw
Quoted 1 line · Slava Pestov

Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found

For completeness, these are the steps are performed, soup to nuts:

# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID:			501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID:		8246b830-95d4-420d-aff8-894efc348801
version:		0
nbuckets:		761856
block_size:		1
bucket_size:		1024
nr_in_set:		1
nr_this_dev:		0
first_bucket:		1
UUID:			261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID:		8246b830-95d4-420d-aff8-894efc348801
version:		1
block_size:		1
data_offset:		16
UUID:			eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID:		8246b830-95d4-420d-aff8-894efc348801
version:		1
block_size:		1
data_offset:		16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct  3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct  3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument
Quoted 22 lines · Stan Hoeppner
Quoted 21 lines
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

What's the problem here?

Thanks,
Stan
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#3 lore raw

It looks like everything went fine, what is the problem?

Quoted 102 lines · Stan Hoeppner
Quoted 1 line · Slava Pestov

Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found

For completeness, these are the steps are performed, soup to nuts:

# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID:                   501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                0
nbuckets:               761856
block_size:             1
bucket_size:            1024
nr_in_set:              1
nr_this_dev:            0
first_bucket:           1
UUID:                   261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
UUID:                   eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct  3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct  3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument
Quoted 22 lines · Stan Hoeppner
Quoted 21 lines
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

What's the problem here?

Thanks,
Stan
--
To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to [email protected]
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#4 lore raw

I assumed it did not go fine due to the immediate error on the echo command. FYI, this is my first attempt at bcache.

bash: echo: write error: Invalid argument

How can I confirm both dm-4 and dm-7 (bcache0 and bcache1) are both attached and that bcache is running?

FYI, this is my first attempt at bcache, so I'm following the instructions precisely. Also, dm-4 and dm-7 are 44 TB RAID6 LUNs. If my testing shows substantial benefit in decreasing RMW we will be looking at deploying bcache with one or more mirrored pairs of SSDs to 14 of these arrays. That's per system. And we'll be deploying 100s of such systems.

I emailed Kent's gmail address about this about a month ago and never received a response. At some point, probably next year some time, the company I'm working for may want to contract with him for a short time before moving into production with this.

Thanks,
Stan

Quoted 105 lines · Slava Pestov

It looks like everything went fine, what is the problem?

Quoted 102 lines · Stan Hoeppner
Quoted 1 line · Slava Pestov

Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found

For completeness, these are the steps are performed, soup to nuts:

# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID:                   501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                0
nbuckets:               761856
block_size:             1
bucket_size:            1024
nr_in_set:              1
nr_this_dev:            0
first_bucket:           1
UUID:                   261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
UUID:                   eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct  3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct  3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument
Quoted 22 lines · Stan Hoeppner
Quoted 21 lines
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

What's the problem here?

Thanks,
Stan
--
To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html

#5 lore raw

Hi Stan,

The 'register' command attaches the backing device, you don't need to do the separate 'attach' step. Perhaps the instructions you are following are out of date.

Slava

Quoted 121 lines · Stan Hoeppner

I assumed it did not go fine due to the immediate error on the echo command. FYI, this is my first attempt at bcache.

bash: echo: write error: Invalid argument

How can I confirm both dm-4 and dm-7 (bcache0 and bcache1) are both attached and that bcache is running?

FYI, this is my first attempt at bcache, so I'm following the instructions precisely. Also, dm-4 and dm-7 are 44 TB RAID6 LUNs. If my testing shows substantial benefit in decreasing RMW we will be looking at deploying bcache with one or more mirrored pairs of SSDs to 14 of these arrays. That's per system. And we'll be deploying 100s of such systems.

I emailed Kent's gmail address about this about a month ago and never received a response. At some point, probably next year some time, the company I'm working for may want to contract with him for a short time before moving into production with this.

Thanks,
Stan

Quoted 105 lines · Slava Pestov

It looks like everything went fine, what is the problem?

Quoted 102 lines · Stan Hoeppner
Quoted 1 line · Slava Pestov

Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found

For completeness, these are the steps are performed, soup to nuts:

# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID:                   501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                0
nbuckets:               761856
block_size:             1
bucket_size:            1024
nr_in_set:              1
nr_this_dev:            0
first_bucket:           1
UUID:                   261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
UUID:                   eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct  3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct  3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument
Quoted 22 lines · Stan Hoeppner
Quoted 21 lines
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

What's the problem here?

Thanks,
Stan
--
To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html

#6 lore raw

Probably so. I'm working from:
https://www.kernel.org/doc/Documentation/bcache.txt

Do I need to manually register the backing devices? I formatted the LUNs and the SSD on the same command line. Instructions above say you don't need to register manually if doing it that way. Also, I'm not using the udev rules, but doing everything manually at this point. And there is a reason for that. I don't have complete control/access to the development system. The rootfs is NFS mounted read only, and changes such as udev rules take days...

Thanks,
Stan

Quoted 130 lines · Slava Pestov

Hi Stan,

The 'register' command attaches the backing device, you don't need to do the separate 'attach' step. Perhaps the instructions you are following are out of date.

Slava

Quoted 121 lines · Stan Hoeppner

I assumed it did not go fine due to the immediate error on the echo command. FYI, this is my first attempt at bcache.

bash: echo: write error: Invalid argument

How can I confirm both dm-4 and dm-7 (bcache0 and bcache1) are both attached and that bcache is running?

FYI, this is my first attempt at bcache, so I'm following the instructions precisely. Also, dm-4 and dm-7 are 44 TB RAID6 LUNs. If my testing shows substantial benefit in decreasing RMW we will be looking at deploying bcache with one or more mirrored pairs of SSDs to 14 of these arrays. That's per system. And we'll be deploying 100s of such systems.

I emailed Kent's gmail address about this about a month ago and never received a response. At some point, probably next year some time, the company I'm working for may want to contract with him for a short time before moving into production with this.

Thanks,
Stan

Quoted 105 lines · Slava Pestov

It looks like everything went fine, what is the problem?

Quoted 102 lines · Stan Hoeppner
Quoted 1 line · Slava Pestov

Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found

For completeness, these are the steps are performed, soup to nuts:

# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID:                   501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                0
nbuckets:               761856
block_size:             1
bucket_size:            1024
nr_in_set:              1
nr_this_dev:            0
first_bucket:           1
UUID:                   261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
UUID:                   eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct  3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct  3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument
Quoted 22 lines · Stan Hoeppner
Quoted 21 lines
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

What's the problem here?

Thanks,
Stan
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#7 lore raw

Hi Stan,

It looks like those docs are out of date. Echoing the names of the cache and backing devices to 'register' is sufficient. 'attach' is for adding a new backing device to an existing cache set after the fact.

Slava

Quoted 141 lines · Stan Hoeppner

Probably so. I'm working from:
https://www.kernel.org/doc/Documentation/bcache.txt

Do I need to manually register the backing devices? I formatted the LUNs and the SSD on the same command line. Instructions above say you don't need to register manually if doing it that way. Also, I'm not using the udev rules, but doing everything manually at this point. And there is a reason for that. I don't have complete control/access to the development system. The rootfs is NFS mounted read only, and changes such as udev rules take days...

Thanks,
Stan

Quoted 130 lines · Slava Pestov

Hi Stan,

The 'register' command attaches the backing device, you don't need to do the separate 'attach' step. Perhaps the instructions you are following are out of date.

Slava

Quoted 121 lines · Stan Hoeppner

I assumed it did not go fine due to the immediate error on the echo command. FYI, this is my first attempt at bcache.

bash: echo: write error: Invalid argument

How can I confirm both dm-4 and dm-7 (bcache0 and bcache1) are both attached and that bcache is running?

FYI, this is my first attempt at bcache, so I'm following the instructions precisely. Also, dm-4 and dm-7 are 44 TB RAID6 LUNs. If my testing shows substantial benefit in decreasing RMW we will be looking at deploying bcache with one or more mirrored pairs of SSDs to 14 of these arrays. That's per system. And we'll be deploying 100s of such systems.

I emailed Kent's gmail address about this about a month ago and never received a response. At some point, probably next year some time, the company I'm working for may want to contract with him for a short time before moving into production with this.

Thanks,
Stan

Quoted 105 lines · Slava Pestov

It looks like everything went fine, what is the problem?

Quoted 102 lines · Stan Hoeppner
Quoted 1 line · Slava Pestov

Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found

For completeness, these are the steps are performed, soup to nuts:

# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID:                   501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                0
nbuckets:               761856
block_size:             1
bucket_size:            1024
nr_in_set:              1
nr_this_dev:            0
first_bucket:           1
UUID:                   261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
UUID:                   eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct  3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct  3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument
Quoted 22 lines · Stan Hoeppner
Quoted 21 lines
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

What's the problem here?

Thanks,
Stan
--
To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html

#8 lore raw

Would you please kindly provide a link to more recent docs? I notice I have a stripe_size file that's not mentioned in any of the docs I have linked, including the official evil pirate docs. I know Kent was working on stripe write optimization in newer versions. I'm on kernel 3.12.26, so that must have been back ported.

Thanks,
Stan

Quoted 150 lines · Slava Pestov

Hi Stan,

It looks like those docs are out of date. Echoing the names of the cache and backing devices to 'register' is sufficient. 'attach' is for adding a new backing device to an existing cache set after the fact.

Slava

Quoted 141 lines · Stan Hoeppner

Probably so. I'm working from:
https://www.kernel.org/doc/Documentation/bcache.txt

Do I need to manually register the backing devices? I formatted the LUNs and the SSD on the same command line. Instructions above say you don't need to register manually if doing it that way. Also, I'm not using the udev rules, but doing everything manually at this point. And there is a reason for that. I don't have complete control/access to the development system. The rootfs is NFS mounted read only, and changes such as udev rules take days...

Thanks,
Stan

Quoted 130 lines · Slava Pestov

Hi Stan,

The 'register' command attaches the backing device, you don't need to do the separate 'attach' step. Perhaps the instructions you are following are out of date.

Slava

Quoted 121 lines · Stan Hoeppner

I assumed it did not go fine due to the immediate error on the echo command. FYI, this is my first attempt at bcache.

bash: echo: write error: Invalid argument

How can I confirm both dm-4 and dm-7 (bcache0 and bcache1) are both attached and that bcache is running?

FYI, this is my first attempt at bcache, so I'm following the instructions precisely. Also, dm-4 and dm-7 are 44 TB RAID6 LUNs. If my testing shows substantial benefit in decreasing RMW we will be looking at deploying bcache with one or more mirrored pairs of SSDs to 14 of these arrays. That's per system. And we'll be deploying 100s of such systems.

I emailed Kent's gmail address about this about a month ago and never received a response. At some point, probably next year some time, the company I'm working for may want to contract with him for a short time before moving into production with this.

Thanks,
Stan

Quoted 105 lines · Slava Pestov

It looks like everything went fine, what is the problem?

Quoted 102 lines · Stan Hoeppner
Quoted 1 line · Slava Pestov

Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found

For completeness, these are the steps are performed, soup to nuts:

# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID:                   501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                0
nbuckets:               761856
block_size:             1
bucket_size:            1024
nr_in_set:              1
nr_this_dev:            0
first_bucket:           1
UUID:                   261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
UUID:                   eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct  3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct  3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument
Quoted 22 lines · Stan Hoeppner
Quoted 21 lines
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

What's the problem here?

Thanks,
Stan
--
To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html

#9 lore raw

Hi Stan,

Is there any chance you could upgrade to a more recent kernel? As far as I know, recent bcache bug fixes are not being backported to older kernels because bcache depends on some block layer changes that went in more recently.

Quoted 157 lines · Stan Hoeppner

Would you please kindly provide a link to more recent docs? I notice I have a stripe_size file that's not mentioned in any of the docs I have linked, including the official evil pirate docs. I know Kent was working on stripe write optimization in newer versions. I'm on kernel 3.12.26, so that must have been back ported.

Thanks,
Stan

Quoted 150 lines · Slava Pestov

Hi Stan,

It looks like those docs are out of date. Echoing the names of the cache and backing devices to 'register' is sufficient. 'attach' is for adding a new backing device to an existing cache set after the fact.

Slava

Quoted 141 lines · Stan Hoeppner

Probably so. I'm working from:
https://www.kernel.org/doc/Documentation/bcache.txt

Do I need to manually register the backing devices? I formatted the LUNs and the SSD on the same command line. Instructions above say you don't need to register manually if doing it that way. Also, I'm not using the udev rules, but doing everything manually at this point. And there is a reason for that. I don't have complete control/access to the development system. The rootfs is NFS mounted read only, and changes such as udev rules take days...

Thanks,
Stan

Quoted 130 lines · Slava Pestov

Hi Stan,

The 'register' command attaches the backing device, you don't need to do the separate 'attach' step. Perhaps the instructions you are following are out of date.

Slava

Quoted 121 lines · Stan Hoeppner

I assumed it did not go fine due to the immediate error on the echo command. FYI, this is my first attempt at bcache.

bash: echo: write error: Invalid argument

How can I confirm both dm-4 and dm-7 (bcache0 and bcache1) are both attached and that bcache is running?

FYI, this is my first attempt at bcache, so I'm following the instructions precisely. Also, dm-4 and dm-7 are 44 TB RAID6 LUNs. If my testing shows substantial benefit in decreasing RMW we will be looking at deploying bcache with one or more mirrored pairs of SSDs to 14 of these arrays. That's per system. And we'll be deploying 100s of such systems.

I emailed Kent's gmail address about this about a month ago and never received a response. At some point, probably next year some time, the company I'm working for may want to contract with him for a short time before moving into production with this.

Thanks,
Stan

Quoted 105 lines · Slava Pestov

It looks like everything went fine, what is the problem?

Quoted 102 lines · Stan Hoeppner
Quoted 1 line · Slava Pestov

Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found

For completeness, these are the steps are performed, soup to nuts:

# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID:                   501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                0
nbuckets:               761856
block_size:             1
bucket_size:            1024
nr_in_set:              1
nr_this_dev:            0
first_bucket:           1
UUID:                   261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
UUID:                   eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct  3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct  3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument
Quoted 22 lines · Stan Hoeppner
Quoted 21 lines
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

What's the problem here?

Thanks,
Stan
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#10 lore raw

I'd actually just like information on how to confirm caching is enabled and working for both of the LUNs mentioned in my long output below. I'm seeing normal write behavior for one, and odd behavior (2x streaming throughput and some apparent permissions issues) for the other. This leads me to believe bcache is active for the 2nd LUN and is causing some breakage while the first LUN is not being cached.

Thanks,
Stan

Quoted 165 lines · Slava Pestov

Hi Stan,

Is there any chance you could upgrade to a more recent kernel? As far as I know, recent bcache bug fixes are not being backported to older kernels because bcache depends on some block layer changes that went in more recently.

Quoted 157 lines · Stan Hoeppner

Would you please kindly provide a link to more recent docs? I notice I have a stripe_size file that's not mentioned in any of the docs I have linked, including the official evil pirate docs. I know Kent was working on stripe write optimization in newer versions. I'm on kernel 3.12.26, so that must have been back ported.

Thanks,
Stan

Quoted 150 lines · Slava Pestov

Hi Stan,

It looks like those docs are out of date. Echoing the names of the cache and backing devices to 'register' is sufficient. 'attach' is for adding a new backing device to an existing cache set after the fact.

Slava

Quoted 141 lines · Stan Hoeppner

Probably so. I'm working from:
https://www.kernel.org/doc/Documentation/bcache.txt

Do I need to manually register the backing devices? I formatted the LUNs and the SSD on the same command line. Instructions above say you don't need to register manually if doing it that way. Also, I'm not using the udev rules, but doing everything manually at this point. And there is a reason for that. I don't have complete control/access to the development system. The rootfs is NFS mounted read only, and changes such as udev rules take days...

Thanks,
Stan

Quoted 130 lines · Slava Pestov

Hi Stan,

The 'register' command attaches the backing device, you don't need to do the separate 'attach' step. Perhaps the instructions you are following are out of date.

Slava

Quoted 121 lines · Stan Hoeppner

I assumed it did not go fine due to the immediate error on the echo command. FYI, this is my first attempt at bcache.

bash: echo: write error: Invalid argument

How can I confirm both dm-4 and dm-7 (bcache0 and bcache1) are both attached and that bcache is running?

FYI, this is my first attempt at bcache, so I'm following the instructions precisely. Also, dm-4 and dm-7 are 44 TB RAID6 LUNs. If my testing shows substantial benefit in decreasing RMW we will be looking at deploying bcache with one or more mirrored pairs of SSDs to 14 of these arrays. That's per system. And we'll be deploying 100s of such systems.

I emailed Kent's gmail address about this about a month ago and never received a response. At some point, probably next year some time, the company I'm working for may want to contract with him for a short time before moving into production with this.

Thanks,
Stan

Quoted 105 lines · Slava Pestov

It looks like everything went fine, what is the problem?

Quoted 102 lines · Stan Hoeppner
Quoted 1 line · Slava Pestov

Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found

For completeness, these are the steps are performed, soup to nuts:

# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID:                   501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                0
nbuckets:               761856
block_size:             1
bucket_size:            1024
nr_in_set:              1
nr_this_dev:            0
first_bucket:           1
UUID:                   261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
UUID:                   eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID:               8246b830-95d4-420d-aff8-894efc348801
version:                1
block_size:             1
data_offset:            16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct  3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct  3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1           isize=256    agcount=44, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=11709285374, imaxpct=5
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument
Quoted 22 lines · Stan Hoeppner
Quoted 21 lines
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root    0 Oct  3 14:39 .
drwxr-xr-x 6 root root    0 Oct  2 16:32 ..
drwxr-xr-x 7 root root    0 Oct  3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct  3 14:39 register
--w------- 1 root root 4096 Oct  3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

What's the problem here?

Thanks,
Stan
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