[Gluster-devel] regression failures on afr/split-brain-resolution

[Raghavendra Gowdappa]

On Tue, Jul 24, 2018 at 6:54 PM, Ravishankar N <ravishankar at redhat.com>
wrote:

>
>
> On 07/24/2018 06:30 PM, Ravishankar N wrote:
>
>
>
> On 07/24/2018 02:56 PM, Raghavendra Gowdappa wrote:
>
> All,
>
> I was trying to debug regression failures on [1] and observed that
> split-brain-resolution.t was failing consistently.
>
> =========================
> TEST 45 (line 88): 0 get_pending_heal_count patchy
> ./tests/basic/afr/split-brain-resolution.t .. 45/45 RESULT 45: 1
> ./tests/basic/afr/split-brain-resolution.t .. Failed 17/45 subtests
>
> Test Summary Report
> -------------------
> ./tests/basic/afr/split-brain-resolution.t (Wstat: 0 Tests: 45 Failed: 17)
>   Failed tests:  24-26, 28-36, 41-45
>
>
> On probing deeper, I observed a curious fact - on most of the failures
> stat was not served from md-cache, but instead was wound down to afr which
> failed stat with EIO as the file was in split brain. So, I did another test:
> * disabled md-cache
> * mount glusterfs with attribute-timeout 0 and entry-timeout 0
>
> Now the test fails always. So, I think the test relied on stat requests
> being absorbed either by kernel attribute cache or md-cache. When its not
> happening stats are reaching afr and resulting in failures of cmds like
> getfattr etc.
>
>
> This indeed seems to be the case.  Is there any way we can avoid the stat?
> When a getfattr is performed on the mount, aren't lookup + getfattr are the
> only fops that need to be hit in gluster?
>
>
> Or should afr allow (f)stat even for replica-2 split-brains because it is
> allowing lookup anyway (lookup cbk contains stat information from one of
> its children) ?
>

I think the question here should be what kind of access we've to provide
for files in split-brain. Once that broader question is answered, we should
think about what fops come under those kinds of access. If
setfattr/getfattr cmd access has to be provided I guess lookup, stat,
setxattr, getxattr need to work with split-brain files.

-Ravi
>
> -Ravi
>
> Thoughts?
>
> [1] https://review.gluster.org/#/c/20549/
>
>
> _______________________________________________
> Gluster-devel mailing listGluster-devel at gluster.orghttps://lists.gluster.org/mailman/listinfo/gluster-devel
>
>
>
>
> _______________________________________________
> Gluster-devel mailing listGluster-devel at gluster.orghttps://lists.gluster.org/mailman/listinfo/gluster-devel
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.gluster.org/pipermail/gluster-devel/attachments/20180725/2fadb53c/attachment.html>