[lvm-devel] lvmcache in writeback mode gets stuck flushing dirty blocks

[Nikhil Kshirsagar]

This used to happen if the chunksize increased as a result of needing to
use more than a million chunks to store the size of the cached lv. What is
the size of the pool?

Regards,
Nikhil.

On Tue, 30 Jul, 2019, 1:25 PM Lakshmi Narasimhan Sundararajan, <
lns at portworx.com> wrote:

> Hi Team,
>
> A very good day to all.
>
>
> I am using lvmcache in writeback mode. When there are dirty blocks still
> in the lv, and if needs to be destroyed or flushed, then
>
> It seems to me that there are some conditions under which the dirty data
> flush gets stuck forever.
>
>
>
>
>
> As an example:
>
> root at pdc4-sm35:~# lvremove -f pwx0/pool
>
>   367 blocks must still be flushed.
>
>   367 blocks must still be flushed.
>
>   367 blocks must still be flushed.
>
>   367 blocks must still be flushed.
>
>   367 blocks must still be flushed.
>
>   367 blocks must still be flushed.
>
> ^C
>
> root at pdc4-sm35:~#
>
>
>
> I am running these version:
>
> root at pdc4-sm35:~# lvm version
>
>   LVM version:     2.02.133(2) (2015-10-30)
>
>   Library version: 1.02.110 (2015-10-30)
>
>   Driver version:  4.34.0
>
> root at pdc4-sm35:~#
>
>
>
>
>
> This issue seems old and reported multiple places. There have been some
> acknowledgement that this issue is resolved in 2.02.133, but still I see
> it. Also, I have seen some posts report it in 2.02.170+ as well (here:
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=878441) (Package: lvm2
> Version: 2.02.173-1 Severity: normal)
>
>
>
> I filed one here myself, https://github.com/lvmteam/lvm2/issues/22,
> trying  to understand from you experts where we are on this?
>
>
>
> I would sincerely appreciate your help in understanding the state of this
> issue in more detail.
>
>
>
> Best regards
> LN
>
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> Windows 10
>
>
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