btrfs device scan
I have a couple computers running 2.6.38 (Ubuntu Natty 2.6.38-8-generic), and on both of them "btrfs device scan" comes back with nothing other than "failed to read /dev/sr0"
One computer has a btrfs RAID-1 volume, and the other has two separate btrfs filesystems. The results are the same whether the filesystems are mounted or not.
Why is "btrfs device scan" not scanning the devices?
vic
Hallo, Victor,
Du meintest am 12.05.11:
Quoted 8 lines
I have a couple computers running 2.6.38 (Ubuntu Natty 2.6.38-8-generic), and on both of them "btrfs device scan" comes back with nothing other than "failed to read
/dev/sr0"One computer has a btrfs RAID-1 volume, and the other has two separate btrfs filesystems. The results are the same whether the filesystems are mounted or not.
What tells
ls /dev/sd*
ls /dev/md*Quoted 1 line
Why is "btrfs device scan" not scanning the devices?
If I have understood the scan routine then it looks for all (?) block devices in "/dev".
Viele Gruesse!
Helmut
Quoted 9 lines · Helmut Hullen
Hallo, Victor,
Du meintest am 12.05.11:
Quoted 4 lines
I have a couple computers running 2.6.38 (Ubuntu Natty 2.6.38-8-generic), and on both of them "btrfs device scan" comes back with nothing other than "failed to read
/dev/sr0"
Quoted 4 lines
What tells
ls /dev/sd* ls /dev/md*
$ ls /dev/sd* /dev/sda /dev/sda1 /dev/sda2 /dev/sda5 /dev/sdb /dev/sdb1 /dev/sdc /dev/sdc1
$ ls /dev/md* ls: cannot access /dev/md*: No such file or directory
$ btrfs device scan Scanning for Btrfs filesystems failed to read /dev/sr0
$ btrfs filesystem show failed to read /dev/sr0 Label: 'server-backup' uuid: b927ead9-2e5b-4ee8-b9f4-7209177c49d8 Total devices 2 FS bytes used 603.17GB devid 1 size 1.36TB used 605.28GB path /dev/sdb1 devid 2 size 1.36TB used 605.26GB path /dev/sdc1
Btrfs Btrfs v0.19
$
Hallo, Victor,
Du meintest am 12.05.11:
Quoted 4 lines
Quoted 4 lines
Quoted 4 lines
I have a couple computers running 2.6.38 (Ubuntu Natty 2.6.38-8-generic), and on both of them "btrfs device scan" comes back with nothing other than "failed to read
/dev/sr0"
[..]
Quoted 3 lines
$ btrfs device scan Scanning for Btrfs filesystems failed to read /dev/sr0
That's a "well known" error; "scan" tries block devices which really cannot contain a btrfs filesystem.
People who don't use "udev" get a lot of more "failed to read" messages; "scan" seems to try every block device which exists in "/dev".
Maybe it's more reliable if "scan" doesn't look into "dev" but uses "/ proc/partitions".
Quoted 6 lines
$ btrfs filesystem show failed to read /dev/sr0 Label: 'server-backup' uuid: b927ead9-2e5b-4ee8-b9f4-7209177c49d8 Total devices 2 FS bytes used 603.17GB devid 1 size 1.36TB used 605.28GB path /dev/sdb1 devid 2 size 1.36TB used 605.26GB path /dev/sdc1
That shows that (in this case) you can ignore the "scan" message.
Viele Gruesse!
Helmut
Quoted 10 lines · Victor Roetman
I have a couple computers running 2.6.38 (Ubuntu Natty 2.6.38-8-generic), and on both of them "btrfs device scan" comes back with nothing other than "failed to read
/dev/sr0"One computer has a btrfs RAID-1 volume, and the other has two separate btrfs filesystems. The results are the same whether the filesystems are mounted or not.
Why is "btrfs device scan" not scanning the devices?
Normally it does not report anything to stdout/stderr. You can see the scan result in dmesg.
-Arne
Quoted 6 lines
vic
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