[CentOS] logical volume is unreadable

Thu Jul 6 13:05:55 UTC 2017
Mike Burger <mburger at bubbanfriends.org>

On 2017-07-06 5:43 am, Volker wrote:
> Hi all,
> 
> one of my lv has become completely unaccessible. Every read access
> results in a buffer io error:
> 
> Buffer I/O error on dev dm-13, logical block 0, async page read
> 
> this goes for every block in the lv. A ddrescue failed on every single
> block.
> 
> 
> $ lvdisplay
>   --- Logical volume ---
>   LV Path                /dev/vg0/lv-vm-tviewer
>   LV Name                lv-vm-tviewer
>   VG Name                vg0
>   LV UUID                XdgHFs-RHVZ-9BAH-1ZSK-yiBX-qqf0-273CtT
>   LV Write Access        read/write
>   LV Creation host, time host1, 2016-02-06 14:58:19 +0100
>   LV snapshot status     INACTIVE destination for lv-vm-tviewer_vorigin
>   LV Status              available
>   # open                 0
>   LV Size                58.59 GiB
>   Current LE             15000
>   COW-table size         5.86 GiB
>   COW-table LE           1500
>   Snapshot chunk size    4.00 KiB
>   Segments               1
>   Allocation             inherit
>   Read ahead sectors     auto
>   - currently set to     8192
>   Block device           253:13
> 
> 
> Other lv on the same volume group are healthy. In fact the whole host
> runs on the same vg and does not show any problems. Physical volume is 
> a
> md raid1 device which is also healthy, as well as its hard disks.
> 
> The faulty lv is used as the storage device for a qemu vm, which
> suddenly stalled when the io-errors appeared on the host.
> 
> 
> Is the any way to diagnose this problem? (centos 7)
> 
> 
> Regards
> .....Volker

Hello, Volker.

Assuming that, at this point, everything that would have been running 
from this LV/FS is down, have you considered unmounting the filesystem 
and running a filesystem check against it?

If it's EXT2/3/4, you can run fsck against it, if it's XFS, you can run 
xfs_repair against it.

-- 
Mike Burger
http://www.bubbanfriends.org

"It's always suicide-mission this, save-the-planet that. No one ever 
just stops by to say 'hi' anymore." --Colonel Jack O'Neill, SG1