On 04/01/2013 02:23 PM, Brian J. Murrell wrote:
I have a VG:
VG #PV #LV #SN Attr VSize VFree
rootvol_tmp 1 26 0 wz--n- 74.40g 32.83g
Which has an LV in it which has a bad disk block on it. Per previous
discussions here I have an LV into which I can remap PEs with bad blocks on them:
# lvdisplay --maps /dev/rootvol_tmp/badblocks
--- Logical volume ---
LV Name /dev/rootvol_tmp/badblocks
VG Name rootvol_tmp
LV UUID oRCTFY-XNxh-3FA5-8lUG-FsOG-GjaO-giAcIu
LV Write Access read/write
LV Status available
# open 0
LV Size 4.00 MiB
Current LE 1
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:2
--- Segments ---
Logical extent 0 to 0:
Type linear
Physical volume /dev/sda2
Physical extents 2805 to 2805
As you can see, it has a PE in it already. I am trying to map another
PE into it but getting an error:
# lvextend --alloc anywhere /dev/rootvol_tmp/badblocks -l +1 /dev/sda2:2812
Extending logical volume badblocks to 8.00 MiB
Insufficient free space: 1 extents needed, but only 0 available
Clearly there is something wrong with my syntax but I'm not quite sure
what it is. Any ideas?
You said there is a LV containing the bad block. You can not have a
block belonging to two LVs (for completeness sake: it is possible in
snapshots but those shared extents can not be created like that ^)
*Is the extent 2812 free?*
*No*
Use something like `pvmove --alloc anywhere /dev/sda2:2812` first.
Known issues: it does not work on mirrors and snapshots.
Workarounds? Split the mirror. Delete snapshot. Or you could try to
hand-edit the metadata.
Also I am unsure what's the granularity of data it would skip - you may
try to extract them first with e.g. ddrescue.
*Yes*
Then I have no idea except you may try specifying range /dev/sda2:2812-2812
Much thanks!
b.
P.S. Please, no lectures about replacing the disk. I understand the risks
of operating on a disk that is starting to show signs of wear. All of
the data on this disk is backed up twice daily and anything lost
between those backups will not be missed. It's just not feasible for me
to replace this disk at this time. Thanks.
I fully respect your choice, I myself have enough of throw away data
like VMs...
Except you may want to consider following:
Just for convenience, if you can spare more than 2 blocks be more
generous and disable larger extent of blocks - those disk errors like to
spread... (or allocate to LV which loosing will be least )
Sometimes backups are not backups. To check if the backups work, have
you ever tried to recover *all* data from those backups?
By size of the disk looks like notebook. Are you using disk encryption?
(Loosing LUKS header could be rather painful! Have you backed up that as
well? Otherwise you would need to restore everything - which may be
impractical for example over slow network or with limited data.)
Similar applies to loosing LVM metadata.
And also depending on FS you may loose more than just few files.
-- Marian
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