lvremove: 'snapshot': can't remove 'active'? , non-mounted file system

linux-lvm Linda A. Walsh 3 participants 3 messages Jun 29, 2010 – Jul 13, 2010

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Linda A. Walsh

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2010-06-29 14:07 UTC #0 lore raw

lvremove -v /dev/Home/2010.06.27-06.18.55
Using logical volume(s) on command line
Can't remove open logical volume "2010.06.27-06.18.55"

But it isn't mounted.

So why is it saying it is 'open':

ll /dev/mapper shows:

crw-rw---- 1 10, 58 2010-02-02 21:08 control

brw-r----- 1 252,  4 2010-02-02 21:08 Home-2010.06.27--06.18.55
brw-r----- 1 252,  3 2010-02-02 21:08 Home-2010.06.27--06.18.55-cow
brw-r----- 1 252,  2 2010-02-02 21:08 Home-Home
brw-r----- 1 252,  1 2010-02-02 21:08 Home-Home-real
brw-r----- 1 252,  0 2010-02-02 21:08 Home-Share
brw-r----- 1 252,  5 2010-02-02 21:08 Space-Backup
brw-r----- 1 252, 11 2010-06-29 06:40 Space-boot
brw-r----- 1 252,  6 2010-06-29 06:40 Space-root
brw-r----- 1 252,  7 2010-06-28 17:45 Space-Torrents
brw-r----- 1 252,  8 2010-06-29 06:40 Space-usr
brw-r----- 1 252,  9 2010-06-29 06:40 Space-var

brw-r----- 1 252, 10 2010-06-29 06:40 Space-var_cache

So 252 is the mapper device?

Is my real Home partition on 252,1?

I just got a backup error when I tried to backup Home, which would correspond to 252,2 above. It thinks it is no longer the same file system as the previous backup,

Should I be backing up Home-Home-real? That doesn't seem right...

Luca Berra

2010-07-13 06:34 UTC #1 lore raw

Quoted 7 lines · Linda A. Walsh

lvremove -v /dev/Home/2010.06.27-06.18.55
Using logical volume(s) on command line
Can't remove open logical volume "2010.06.27-06.18.55"
But it isn't mounted.
So why is it saying it is 'open':

something is using it
try looking in /sys/block/dm-4/holders, fuser, lsof ...

Quoted 15 lines

ll /dev/mapper shows:

crw-rw---- 1 10, 58 2010-02-02 21:08 control

brw-r----- 1 252,  4 2010-02-02 21:08 Home-2010.06.27--06.18.55
brw-r----- 1 252,  3 2010-02-02 21:08 Home-2010.06.27--06.18.55-cow
brw-r----- 1 252,  2 2010-02-02 21:08 Home-Home
brw-r----- 1 252,  1 2010-02-02 21:08 Home-Home-real
brw-r----- 1 252,  0 2010-02-02 21:08 Home-Share
brw-r----- 1 252,  5 2010-02-02 21:08 Space-Backup
brw-r----- 1 252, 11 2010-06-29 06:40 Space-boot
brw-r----- 1 252,  6 2010-06-29 06:40 Space-root
brw-r----- 1 252,  7 2010-06-28 17:45 Space-Torrents
brw-r----- 1 252,  8 2010-06-29 06:40 Space-usr
brw-r----- 1 252,  9 2010-06-29 06:40 Space-var

Quoted 3 lines

brw-r----- 1 252, 10 2010-06-29 06:40 Space-var_cache
So 252 is the mapper device?

252 is the dynamic major assigned to device-mapper on your system

Quoted 1 line

Is my real Home partition on 252,1?

before you created the snapshot your Home device was /dev/mapper/Home-Home (aka dm-2)
in order to create a snapshot lvm will use 4 devices
1) Home-Home-real (linear) which has the same mapping as Home-Home before the snapshot took place
2) Home-2010.06.27--06.18.55-cow (linear) which maps the space that will contains the COW data
3) Home-2010.06.27--06.18.55 (snapshot) this is a combination of (1) and
(2) in order to show the visible snapshot
4) Home-Home (snapshot-origin) this device replaces your Home device (keeping the same minor number)

so after taking the snapshot your Home device is still /dev/mapper/Home-Home, which maps to /dev/mapper/Home-Home-real, but before any write to /dev/mapper/Home-Home-real the original data is saved to Home-2010.06.27--06.18.55-cow, so Home-2010.06.27--06.18.55 (which is based on Home-Home-real and Home-2010.06.27--06.18.55-cow) will not change

please look also at linux/Documentation/device-mapper/snapshot.txt

Quoted 3 lines

I just got a backup error when I tried to backup Home, which would correspond to 252,2 above. It thinks it is no longer the same file system as the previous backup,

details please

Quoted 2 lines

Should I be backing up Home-Home-real? That doesn't seem right...

usually one backs up the snapshot, which is supposed to be a point-in-time copy of the original, so i think you should backup Home-2010.06.27--06.18.55

Signature · 6 lines

Luca Berra -- [email protected]
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Ray Morris

2010-07-13 10:23 UTC #2 lore raw

Quoted 3 lines

Quoted 3 lines
lvremove -v /dev/Home/2010.06.27-06.18.55
Using logical volume(s) on command line
Can't remove open logical volume "2010.06.27-06.18.55"

Does it have a partition which needs to be "released"? with kpartx
-dv?
Try ls -al /dev/Home/2010.06.27-06.18.55*
--
Ray Morris
[email protected]

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Quoted 81 lines · Luca Berra

Quoted 7 lines · Linda A. Walsh
lvremove -v /dev/Home/2010.06.27-06.18.55
Using logical volume(s) on command line
Can't remove open logical volume "2010.06.27-06.18.55"
But it isn't mounted.
So why is it saying it is 'open':
something is using it
try looking in /sys/block/dm-4/holders, fuser, lsof ...
Quoted 15 lines
ll /dev/mapper shows:
crw-rw---- 1 10, 58 2010-02-02 21:08 control
brw-r----- 1 252,  4 2010-02-02 21:08 Home-2010.06.27--06.18.55
brw-r----- 1 252,  3 2010-02-02 21:08 Home-2010.06.27--06.18.55-cow
brw-r----- 1 252,  2 2010-02-02 21:08 Home-Home
brw-r----- 1 252,  1 2010-02-02 21:08 Home-Home-real
brw-r----- 1 252,  0 2010-02-02 21:08 Home-Share
brw-r----- 1 252,  5 2010-02-02 21:08 Space-Backup
brw-r----- 1 252, 11 2010-06-29 06:40 Space-boot
brw-r----- 1 252,  6 2010-06-29 06:40 Space-root
brw-r----- 1 252,  7 2010-06-28 17:45 Space-Torrents
brw-r----- 1 252,  8 2010-06-29 06:40 Space-usr
brw-r----- 1 252,  9 2010-06-29 06:40 Space-var
Quoted 3 lines
brw-r----- 1 252, 10 2010-06-29 06:40 Space-var_cache
So 252 is the mapper device?
252 is the dynamic major assigned to device-mapper on your system
Quoted 1 line
Is my real Home partition on 252,1?
before you created the snapshot your Home device was /dev/mapper/Home-Home (aka dm-2)
in order to create a snapshot lvm will use 4 devices
1) Home-Home-real (linear) which has the same mapping as Home-Home before the snapshot took place
2) Home-2010.06.27--06.18.55-cow (linear) which maps the space that will contains the COW data
3) Home-2010.06.27--06.18.55 (snapshot) this is a combination of (1) and
(2) in order to show the visible snapshot
4) Home-Home (snapshot-origin) this device replaces your Home device (keeping the same minor number)
so after taking the snapshot your Home device is still /dev/mapper/Home-Home, which maps to /dev/mapper/Home-Home-real, but before any write to /dev/mapper/Home-Home-real the original data is saved to Home-2010.06.27--06.18.55-cow, so Home-2010.06.27--06.18.55 (which is based on Home-Home-real and Home-2010.06.27--06.18.55-cow) will not change
please look also at linux/Documentation/device-mapper/snapshot.txt
Quoted 3 lines
I just got a backup error when I tried to backup Home, which would correspond to 252,2 above. It thinks it is no longer the same file system as the previous backup,
details please
Quoted 2 lines
Should I be backing up Home-Home-real? That doesn't seem right...
usually one backs up the snapshot, which is supposed to be a point-in-time copy of the original, so i think you should backup Home-2010.06.27--06.18.55
L.
Signature · 12 lines
Luca Berra -- [email protected]
        Communication Media & Services S.r.l.
 /"\
 \ /     ASCII RIBBON CAMPAIGN
  X        AGAINST HTML MAIL
 / \

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