[Gluster-users] GFID Mismatch - Automatic Correction ?

Wed Jan 4 07:28:15 UTC 2017

Hi,

Sorry, one thing I meant to mention and forgot.. just in case it is relevant at all, this was initially a 2 node gluster volume, and the arbiter was added later.

Regards,
Michael Ward.

From: Ravishankar N [mailto:ravishankar at redhat.com]
Sent: Wednesday, 4 January 2017 4:22 PM
To: Michael Ward <Michael.Ward at melbourneit.com.au>; gluster-users at gluster.org
Subject: Re: [Gluster-users] GFID Mismatch - Automatic Correction ?

On 01/04/2017 09:31 AM, Michael Ward wrote:
Hey,

To give some more context around the initial incident.. These systems are hosted in AWS. The gluster brick for each instance is a seperate volume to the root volume. On prod-gluster01 a couple of nights ago we experienced massively high read iops on the root volume that we are unable to account for (> 200,000 iops when it usually sits between 0 - 100 iops ). The box became inaccessible as a result and after approximately 40 minutes with no sign of the iops reducing was rebooted through the AWS console.

The GFID mismatch problems appeared after that. There were initially ~50 impacted files, but I've fixed all but 1 of them now, which I'm leaving broken intentionally for further testing if required.

If you don't mind, could you have a look over the information below and identify anything that looks like a problem, since obviously we did have a bunch of GFID mismatched files, which based on your email shouldn't happen..

I've included everything I can think of, but if there is something else you would like to see, please let me know.

# gluster volume info gv0

Volume Name: gv0
Type: Replicate
Volume ID: 0ec7c49d-811c-4d4d-a3a9-e4ea9e83000c
Status: Started
Snapshot Count: 0
Number of Bricks: 1 x (2 + 1) = 3
Transport-type: tcp
Bricks:
Brick1: prod-gluster01.fqdn.com:/export/glus_brick0/brick
Brick2: prod-gluster02.fqdn.com:/export/glus_brick0/brick
Brick3: prod-gluster03.fqdn.com:/export/glus_brick0/brick (arbiter)
Options Reconfigured:
cluster.favorite-child-policy: none
nfs.disable: on
performance.readdir-ahead: on
client.event-threads: 7
server.event-threads: 3
performance.cache-size: 256MB

cluster.favorite-child-policy is set to none because I reverted the change to majority when it didn't make any difference.

[root at prod-gluster01 glusterfs]# getfattr -d -m . -e hex /export/glus_brick0/brick/home/user/.viminfo
getfattr: Removing leading '/' from absolute path names
# file: export/glus_brick0/brick/home/user/.viminfo
security.selinux=0x73797374656d5f753a6f626a6563745f723a756e6c6162656c65645f743a733000
trusted.afr.dirty=0x000000000000000000000000
trusted.bit-rot.version=0x0200000000000000585756be00024333
trusted.gfid=0x1b86a5a76e884f40be583fa33aa9a576

[root at prod-gluster02 glusterfs]# getfattr -d -m . -e hex /export/glus_brick0/brick/home/user/.viminfo
getfattr: Removing leading '/' from absolute path names
# file: export/glus_brick0/brick/home/user/.viminfo
security.selinux=0x73797374656d5f753a6f626a6563745f723a756e6c6162656c65645f743a733000
trusted.afr.dirty=0x000000000000000000000000
trusted.afr.gv0-client-0=0x000000020000000100000000
trusted.bit-rot.version=0x020000000000000058593aac000661fa
trusted.gfid=0x4931b10977f34496a7cdf8f23809c372

[root at prod-gluster03 glusterfs]# getfattr -d -m . -e hex /export/glus_brick0/brick/home/user/.viminfo
getfattr: Removing leading '/' from absolute path names
# file: export/glus_brick0/brick/home/user/.viminfo
security.selinux=0x73797374656d5f753a6f626a6563745f723a756e6c6162656c65645f743a733000
trusted.afr.dirty=0x000000000000000000000000
trusted.afr.gv0-client-0=0x000000020000000100000000
trusted.bit-rot.version=0x020000000000000058585ed6000f2077
trusted.gfid=0x4931b10977f34496a7cdf8f23809c372

Just in case it's useful, here is the getfattr for the parent directory:

[root at prod-gluster01 glusterfs]# getfattr -d -m . -e hex /export/glus_brick0/brick/home/user
getfattr: Removing leading '/' from absolute path names
# file: export/glus_brick0/brick/home/user
security.selinux=0x73797374656d5f753a6f626a6563745f723a756e6c6162656c65645f743a733000
trusted.afr.dirty=0x000000000000000000000000
trusted.afr.gv0-client-1=0x000000000000000000000000
trusted.afr.gv0-client-2=0x000000000000000000000000
trusted.gfid=0x0a49de7ee4f04aae9fc8a88378e0d193
trusted.glusterfs.dht=0x000000010000000000000000ffffffff

[root at prod-gluster02 glusterfs]# getfattr -d -m . -e hex /export/glus_brick0/brick/home/user
getfattr: Removing leading '/' from absolute path names
# file: export/glus_brick0/brick/home/user
security.selinux=0x73797374656d5f753a6f626a6563745f723a756e6c6162656c65645f743a733000
trusted.afr.dirty=0x000000000000000000000000
trusted.afr.gv0-client-0=0x000000000000000000000000
trusted.afr.gv0-client-2=0x000000000000000000000000
trusted.gfid=0x0a49de7ee4f04aae9fc8a88378e0d193
trusted.glusterfs.dht=0x000000010000000000000000ffffffff

[root at prod-gluster03 glusterfs]# getfattr -d -m . -e hex /export/glus_brick0/brick/home/user
getfattr: Removing leading '/' from absolute path names
# file: export/glus_brick0/brick/home/user
security.selinux=0x73797374656d5f753a6f626a6563745f723a756e6c6162656c65645f743a733000
trusted.afr.dirty=0x000000000000000000000000
trusted.afr.gv0-client-0=0x000000000000000000000000
trusted.afr.gv0-client-1=0x000000000000000000000000
trusted.afr.gv0-client-2=0x000000000000000000000000
trusted.gfid=0x0a49de7ee4f04aae9fc8a88378e0d193
trusted.glusterfs.dht=0x000000010000000000000000ffffffff

[root at prod-gluster01 bricks]# gluster volume heal gv0 info
Brick prod-gluster01.fqdn.com:/export/glus_brick0/brick
Status: Connected
Number of entries: 0

Brick prod-gluster02.fqdn.com:/export/glus_brick0/brick
<gfid:4931b109-77f3-4496-a7cd-f8f23809c372>
Status: Connected
Number of entries: 1

Brick prod-gluster03.fqdn.com:/export/glus_brick0/brick
<gfid:4931b109-77f3-4496-a7cd-f8f23809c372>
Status: Connected
Number of entries: 1

[root at prod-gluster01 bricks]# gluster volume heal gv0 info split-brain
Brick prod-gluster01.fqdn.com:/export/glus_brick0/brick
Status: Connected
Number of entries in split-brain: 0

Brick prod-gluster02.fqdn.com:/export/glus_brick0/brick
Status: Connected
Number of entries in split-brain: 0

Brick prod-gluster03.fqdn.com:/export/glus_brick0/brick
Status: Connected
Number of entries in split-brain: 0

Clients show this in the gluster.log:

[2017-01-04 03:13:40.863695] W [MSGID: 108008] [afr-self-heal-name.c:354:afr_selfheal_name_gfid_mismatch_check] 0-gv0-replicate-0: GFID mismatch for <gfid:0a49de7e-e4f0-4aae-9fc8-a88378e0d193>/.viminfo 4931b109-77f3-4496-a7cd-f8f23809c372 on gv0-client-1 and 1b86a5a7-6e88-4f40-be58-3fa33aa9a576 on gv0-client-0
[2017-01-04 03:13:40.867853] W [fuse-bridge.c:471:fuse_entry_cbk] 0-glusterfs-fuse: 13067223: LOOKUP() /home/user/.viminfo => -1 (Input/output error)
There's no mention of either of the GFID's for the .viminfo file in /var/log/gluster/*.log or /var/log/gluster/brick/export-glus_brick0-brick.log file.

Thanks for the details Michael. While it does look like a bug, I am not sure how we ended in this state. Either the afr xattrs of the parent directory were cleared without self-heal of .vimrc  happening from gluster02 or 03 to 01  (or) it wasn't set in the first place when the file was recreated on 02 and 03 when 01 was down. If you have some steps to re-create the issue, please raise a bug.

Regards,
Ravi

Thank you very much for your time,
Michael Ward

From: Ravishankar N [mailto:ravishankar at redhat.com]
Sent: Wednesday, 4 January 2017 12:21 PM
To: Michael Ward <Michael.Ward at melbourneit.com.au><mailto:Michael.Ward at melbourneit.com.au>; gluster-users at gluster.org<mailto:gluster-users at gluster.org>
Subject: Re: [Gluster-users] GFID Mismatch - Automatic Correction ?

On 01/04/2017 06:27 AM, Michael Ward wrote:
Hi,

We have a 2 data node plus 1 arbiter node replicate gluster volume running gluster 3.8.5. Clients are also using 3.8.5.

One of the data nodes failed the other night, and whilst it was down, several files were replaced on the second data node / arbiter (and thus the filesystem path was linked to a new GFID).

When the broken node was restarted, these files were in a gfid mismatch state. I know how to manually correct them, but was wondering if there is an automated way ?
For resolving gfid-split-brains, there is no automated way or favorite-child policy. When you say 2 data+1 arbiter, you are using an actual arbiter volume right? (as opposed to a replica 2 volume + a dummy node which some people are referring to as arbiter for server-quourm). gfid-split-brains should not occur on either replica-3 or arbiter volumes with the steps you described.
Regards,
Ravi

I thought the cluster.favorite-child-policy volume setting of majority would work, but it made no difference. Clients were still getting Input/output error when attempting to access those files.

Regards,
Michael Ward

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