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Re: [linux-lvm] Insufficient free space: 1 extents needed, but only 0 available with 32.83g available



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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