[Gluster-users] Gluster replicate 3 arbiter 1 in split brain. gluster cli seems unaware

Fri Dec 22 06:26:07 UTC 2017

Hi Henrik,

Thanks for providing the required outputs. See my replies inline.

On Thu, Dec 21, 2017 at 10:42 PM, Henrik Juul Pedersen <hjp at liab.dk> wrote:

> Hi Karthik and Ben,
>
> I'll try and reply to you inline.
>
> On 21 December 2017 at 07:18, Karthik Subrahmanya <ksubrahm at redhat.com>
> wrote:
> > Hey,
> >
> > Can you give us the volume info output for this volume?
>
> # gluster volume info virt_images
>
> Volume Name: virt_images
> Type: Replicate
> Volume ID: 9f3c8273-4d9d-4af2-a4e7-4cb4a51e3594
> Status: Started
> Snapshot Count: 2
> Number of Bricks: 1 x (2 + 1) = 3
> Transport-type: tcp
> Bricks:
> Brick1: virt3:/data/virt_images/brick
> Brick2: virt2:/data/virt_images/brick
> Brick3: printserver:/data/virt_images/brick (arbiter)
> Options Reconfigured:
> features.quota-deem-statfs: on
> features.inode-quota: on
> features.quota: on
> features.barrier: disable
> features.scrub: Active
> features.bitrot: on
> nfs.rpc-auth-allow: on
> server.allow-insecure: on
> user.cifs: off
> features.shard: off
> cluster.shd-wait-qlength: 10000
> cluster.locking-scheme: granular
> cluster.data-self-heal-algorithm: full
> cluster.server-quorum-type: server
> cluster.quorum-type: auto
> cluster.eager-lock: enable
> network.remote-dio: enable
> performance.low-prio-threads: 32
> performance.io-cache: off
> performance.read-ahead: off
> performance.quick-read: off
> nfs.disable: on
> transport.address-family: inet
> server.outstanding-rpc-limit: 512
>
> > Why are you not able to get the xattrs from arbiter brick? It is the same
> > way as you do it on data bricks.
>
> Yes I must have confused myself yesterday somehow, here it is in full
> from all three bricks:
>
> Brick 1 (virt2): # getfattr -d -m . -e hex fedora27.qcow2
> # file: fedora27.qcow2
> trusted.afr.dirty=0x000000000000000000000000
> trusted.afr.virt_images-client-1=0x000002280000000000000000
> trusted.afr.virt_images-client-3=0x000000000000000000000000
> trusted.bit-rot.version=0x1d000000000000005a3aa0db000c6563
> trusted.gfid=0x7a36937d52fc4b55a93299e2328f02ba
> trusted.gfid2path.c076c6ac27a43012=0x30303030303030302d303030302d
> 303030302d303030302d3030303030303030303030312f6665646f726132372e71636f7732
> trusted.glusterfs.quota.00000000-0000-0000-0000-000000000001.contri.1=
> 0x00000000a49eb0000000000000000001
> trusted.pgfid.00000000-0000-0000-0000-000000000001=0x00000001
>
> Brick 2 (virt3): # getfattr -d -m . -e hex fedora27.qcow2
> # file: fedora27.qcow2
> trusted.afr.dirty=0x000000000000000000000000
> trusted.afr.virt_images-client-2=0x000003ef0000000000000000
> trusted.afr.virt_images-client-3=0x000000000000000000000000
> trusted.bit-rot.version=0x19000000000000005a3a9f82000c382a
> trusted.gfid=0x7a36937d52fc4b55a93299e2328f02ba
> trusted.gfid2path.c076c6ac27a43012=0x30303030303030302d303030302d
> 303030302d303030302d3030303030303030303030312f6665646f726132372e71636f7732
> trusted.glusterfs.quota.00000000-0000-0000-0000-000000000001.contri.1=
> 0x00000000a2fbe0000000000000000001
> trusted.pgfid.00000000-0000-0000-0000-000000000001=0x00000001
>
> Brick 3 - arbiter (printserver): # getfattr -d -m . -e hex fedora27.qcow2
> # file: fedora27.qcow2
> trusted.afr.dirty=0x000000000000000000000000
> trusted.afr.virt_images-client-1=0x000002280000000000000000
> trusted.bit-rot.version=0x31000000000000005a39237200073206
> trusted.gfid=0x7a36937d52fc4b55a93299e2328f02ba
> trusted.gfid2path.c076c6ac27a43012=0x30303030303030302d303030302d
> 303030302d303030302d3030303030303030303030312f6665646f726132372e71636f7732
> trusted.glusterfs.quota.00000000-0000-0000-0000-000000000001.contri.1=
> 0x00000000000000000000000000000001
> trusted.pgfid.00000000-0000-0000-0000-000000000001=0x00000001
>
> I was expecting trusted.afr.virt_images-client-{1,2,3} on all bricks?
>
>From AFR-V2 we do not have  self blaming attrs. So you will see a brick
blaming other bricks only.
For example brcik1 can blame brick2 & brick 3, not itself.

>
> > The changelog xattrs are named trusted.afr.virt_images-client-{1,2,3}
> in the
> > getxattr outputs you have provided.
> > Did you do a remove-brick and add-brick any time? Otherwise it will be
> > trusted.afr.virt_images-client-{0,1,2} usually.
>
> Yes, the bricks was moved around initially; brick 0 was re-created as
> brick 2, and the arbiter was added later on as well.
>
> >
> > To overcome this scenario you can do what Ben Turner had suggested.
> Select
> > the source copy and change the xattrs manually.
>
> I won't mind doing that, but again, the guides assume that I have
> trusted.afr.virt_images-client-{1,2,3} on all bricks, so I'm not sure
> what to change to what, where.

> > I am suspecting that it has hit the arbiter becoming source for data heal
> > bug. But to confirm that we need the xattrs on the arbiter brick also.
> >
> > Regards,
> > Karthik
> >
> >
> > On Thu, Dec 21, 2017 at 9:55 AM, Ben Turner <bturner at redhat.com> wrote:
> >>
> >> Here is the process for resolving split brain on replica 2:
> >>
> >>
> >> https://access.redhat.com/documentation/en-US/Red_Hat_Storage/2.1/html/
> Administration_Guide/Recovering_from_File_Split-brain.html
> >>
> >> It should be pretty much the same for replica 3, you change the xattrs
> >> with something like:
> >>
> >> # setfattr -n trusted.afr.vol-client-0 -v 0x000000000000000100000000
> >> /gfs/brick-b/a
> >>
> >> When I try to decide which copy to use I normally run things like:
> >>
> >> # stat /<path to brick>/pat/to/file
> >>
> >> Check out the access and change times of the file on the back end
> bricks.
> >> I normally pick the copy with the latest access / change times.  I'll
> also
> >> check:
> >>
> >> # md5sum /<path to brick>/pat/to/file
> >>
> >> Compare the hashes of the file on both bricks to see if the data
> actually
> >> differs.  If the data is the same it makes choosing the proper replica
> >> easier.
>
> The files on the bricks differ, so there was something changed, and
> not replicated.
>
> Thanks for the input, I've looked at that, but couldn't get it to fit,
> as I dont have trusted.afr.virt_images-client-{1,2,3} on all bricks.
>
You can choose any one of the copy as good based on the latest ctime/mtime.
Before doing anything keep the backup of both the copies, so that if
something bad happens,
you will have the data safe.
Now choose one copy as good (based on timestamps/size/choosing a brick as
source),
and reset the xattrs set for that on other brick. Then do lookup on that
file from the mount.
That should resolve the issue.
Once you are done, please let us know the result.

Regards,
Karthik

>
> >>
> >> Any idea how you got in this situation?  Did you have a loss of NW
> >> connectivity?  I see you are using server side quorum, maybe check the
> logs
> >> for any loss of quorum?  I wonder if there was a loos of quorum and
> there
> >> was some sort of race condition hit:
> >>
> >>
> >> http://docs.gluster.org/en/latest/Administrator%20Guide/
> arbiter-volumes-and-quorum/#server-quorum-and-some-pitfalls
> >>
> >> "Unlike in client-quorum where the volume becomes read-only when quorum
> is
> >> lost, loss of server-quorum in a particular node makes glusterd kill the
> >> brick processes on that node (for the participating volumes) making even
> >> reads impossible."
>
> I might have had a loss of server quorum, but I cant seem to see
> exactly why or when from the logs:
>
> Times are synchronized between servers. Virt 3 was rebooted for
> service at 17:29:39. The shutdown logs show an issue with unmounting
> the bricks, probably because glusterd was still running:
> Dec 20 17:29:39 virt3 systemd[1]: Failed unmounting /data/virt_images.
> Dec 20 17:29:39 virt3 systemd[1]: data-filserver.mount: Mount process
> exited, code=exited status=32
> Dec 20 17:29:39 virt3 systemd[1]: Failed unmounting /data/filserver.
> Dec 20 17:29:39 virt3 systemd[1]: Unmounted /virt_images.
> Dec 20 17:29:39 virt3 systemd[1]: Stopped target Network is Online.
> Dec 20 17:29:39 virt3 systemd[1]: Stopping GlusterFS, a clustered
> file-system server...
> Dec 20 17:29:39 virt3 systemd[1]: Stopping Network Name Resolution...
> Dec 20 17:29:39 virt3 systemd[1]: Stopped GlusterFS, a clustered
> file-system server.
>
> I believe it was around this time, the virtual machine (running on
> virt2) was stopped by qemu.
>
>
> Brick 1 (virt2) only experienced loss of quorum when starting gluster
> (glusterd.log confirms this):
> Dec 20 17:22:03 virt2 systemd[1]: Starting GlusterFS, a clustered
> file-system server...
> Dec 20 17:22:05 virt2 glusterd[739]: [2017-12-20 16:22:05.997472] C
> [MSGID: 106002]
> [glusterd-server-quorum.c:355:glusterd_do_volume_quorum_action]
> 0-management: Server quorum lost for volume filserver. Stopping local
> bricks.
> Dec 20 17:22:05 virt2 glusterd[739]: [2017-12-20 16:22:05.997666] C
> [MSGID: 106002]
> [glusterd-server-quorum.c:355:glusterd_do_volume_quorum_action]
> 0-management: Server quorum lost for volume virt_images. Stopping
> local bricks.
> Dec 20 17:22:06 virt2 systemd[1]: Started GlusterFS, a clustered
> file-system server.
> Dec 20 17:22:11 virt2 glusterd[739]: [2017-12-20 16:22:11.387238] C
> [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume filserver. Starting
> local bricks.
> Dec 20 17:22:11 virt2 glusterd[739]: [2017-12-20 16:22:11.390417] C
> [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume virt_images. Starting
> local bricks.
> -- Reboot --
> Dec 20 18:41:35 virt2 systemd[1]: Starting GlusterFS, a clustered
> file-system server...
> Dec 20 18:41:41 virt2 systemd[1]: Started GlusterFS, a clustered
> file-system server.
> Dec 20 18:41:43 virt2 glusterd[748]: [2017-12-20 17:41:43.387633] C
> [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume filserver. Starting
> local bricks.
> Dec 20 18:41:43 virt2 glusterd[748]: [2017-12-20 17:41:43.391080] C
> [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume virt_images. Starting
> local bricks.
>
>
> Brick 2 (virt3) shows a network outage on the 19th, but everything
> worked fine afterwards:
> Dec 19 13:11:34 virt3 glusterd[10058]: [2017-12-19 12:11:34.382207] C
> [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume filserver. Starting
> local bricks.
> Dec 19 13:11:34 virt3 glusterd[10058]: [2017-12-19 12:11:34.387324] C
> [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume virt_images. Starting
> local bricks.
> Dec 20 17:29:39 virt3 systemd[1]: Stopping GlusterFS, a clustered
> file-system server...
> Dec 20 17:29:39 virt3 systemd[1]: Stopped GlusterFS, a clustered
> file-system server.
> -- Reboot --
> Dec 20 17:30:21 virt3 systemd[1]: Starting GlusterFS, a clustered
> file-system server...
> Dec 20 17:30:22 virt3 glusterd[394]: [2017-12-20 16:30:22.826828] C
> [MSGID: 106002]
> [glusterd-server-quorum.c:355:glusterd_do_volume_quorum_action]
> 0-management: Server quorum lost for volume filserver. Stopping local
> bricks.
> Dec 20 17:30:22 virt3 glusterd[394]: [2017-12-20 16:30:22.827188] C
> [MSGID: 106002]
> [glusterd-server-quorum.c:355:glusterd_do_volume_quorum_action]
> 0-management: Server quorum lost for volume virt_images. Stopping
> local bricks.
> Dec 20 17:30:23 virt3 systemd[1]: Started GlusterFS, a clustered
> file-system server.
> Dec 20 17:30:29 virt3 glusterd[394]: [2017-12-20 16:30:29.488000] C
> [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume filserver. Starting
> local bricks.
> Dec 20 17:30:29 virt3 glusterd[394]: [2017-12-20 16:30:29.491446] C
> [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume virt_images. Starting
> local bricks.
> Dec 20 18:31:06 virt3 systemd[1]: Stopping GlusterFS, a clustered
> file-system server...
> Dec 20 18:31:06 virt3 systemd[1]: Stopped GlusterFS, a clustered
> file-system server.
> -- Reboot --
> Dec 20 18:31:46 virt3 systemd[1]: Starting GlusterFS, a clustered
> file-system server...
> Dec 20 18:31:46 virt3 glusterd[386]: [2017-12-20 17:31:46.958818] C
> [MSGID: 106002]
> [glusterd-server-quorum.c:355:glusterd_do_volume_quorum_action]
> 0-management: Server quorum lost for volume filserver. Stopping local
> bricks.
> Dec 20 18:31:46 virt3 glusterd[386]: [2017-12-20 17:31:46.959168] C
> [MSGID: 106002]
> [glusterd-server-quorum.c:355:glusterd_do_volume_quorum_action]
> 0-management: Server quorum lost for volume virt_images. Stopping
> local bricks.
> Dec 20 18:31:47 virt3 systemd[1]: Started GlusterFS, a clustered
> file-system server.
> Dec 20 18:33:10 virt3 glusterd[386]: [2017-12-20 17:33:10.156180] C
> [MSGID: 106001]
> [glusterd-volume-ops.c:1534:glusterd_op_stage_start_volume]
> 0-management: Server quorum not met. Rejecting operation.
> Dec 20 18:35:58 virt3 glusterd[386]: [2017-12-20 17:35:58.440395] C
> [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume filserver. Starting
> local bricks.
> Dec 20 18:35:58 virt3 glusterd[386]: [2017-12-20 17:35:58.446203] C
> [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume virt_images. Starting
> local bricks.
>
> Brick 3 - arbiter (printserver) shows no loss of quorum at that time
> (again, glusterd.log confirms):
> Dec 19 15:33:24 printserver systemd[1]: Starting GlusterFS, a
> clustered file-system server...
> Dec 19 15:33:26 printserver glusterd[306]: [2017-12-19
> 14:33:26.432369] C [MSGID: 106002]
> [glusterd-server-quorum.c:355:glusterd_do_volume_quorum_action]
> 0-management: Server quorum lost for volume filserver. Stopping local
> bricks.
> Dec 19 15:33:26 printserver glusterd[306]: [2017-12-19
> 14:33:26.432606] C [MSGID: 106002]
> [glusterd-server-quorum.c:355:glusterd_do_volume_quorum_action]
> 0-management: Server quorum lost for volume virt_images. Stopping
> local bricks.
> Dec 19 15:33:26 printserver systemd[1]: Started GlusterFS, a clustered
> file-system server.
> Dec 19 15:34:18 printserver glusterd[306]: [2017-12-19
> 14:34:18.158756] C [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume filserver. Starting
> local bricks.
> Dec 19 15:34:18 printserver glusterd[306]: [2017-12-19
> 14:34:18.162242] C [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume virt_images. Starting
> local bricks.
> Dec 20 18:28:52 printserver systemd[1]: Stopping GlusterFS, a
> clustered file-system server...
> Dec 20 18:28:52 printserver systemd[1]: Stopped GlusterFS, a clustered
> file-system server.
> -- Reboot --
> Dec 20 18:30:40 printserver systemd[1]: Starting GlusterFS, a
> clustered file-system server...
> Dec 20 18:30:42 printserver glusterd[278]: [2017-12-20
> 17:30:42.441675] C [MSGID: 106002]
> [glusterd-server-quorum.c:355:glusterd_do_volume_quorum_action]
> 0-management: Server quorum lost for volume filserver. Stopping local
> bricks.
> Dec 20 18:30:42 printserver glusterd[278]: [2017-12-20
> 17:30:42.441929] C [MSGID: 106002]
> [glusterd-server-quorum.c:355:glusterd_do_volume_quorum_action]
> 0-management: Server quorum lost for volume virt_images. Stopping
> local bricks.
> Dec 20 18:30:42 printserver systemd[1]: Started GlusterFS, a clustered
> file-system server.
> Dec 20 18:33:49 printserver glusterd[278]: [2017-12-20
> 17:33:49.005534] C [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume filserver. Starting
> local bricks.
> Dec 20 18:33:49 printserver glusterd[278]: [2017-12-20
> 17:33:49.008010] C [MSGID: 106003]
> [glusterd-server-quorum.c:349:glusterd_do_volume_quorum_action]
> 0-management: Server quorum regained for volume virt_images. Starting
> local bricks.
>
> >>
> >> I wonder if the killing of brick processes could have led to some sort
> of
> >> race condition where writes were serviced on one brick / the arbiter
> and not
> >> the other?
> >>
> >> If you can find a reproducer for this please open a BZ with it, I have
> >> been seeing something similar(I think) but I haven't been able to run
> the
> >> issue down yet.
> >>
> >> -b
>
> I'm not sure if I can replicate this, a lot has been going on in my
> setup the past few days (trying to tune some horrible small-file and
> file creation/deletion performance).
>
> Thanks for looking into this with me.
>
> Best regards,
> Henrik Juul Pedersen
> LIAB ApS
>
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