[Gluster-users] Copy operation freezes. Lots of locks in state BLOCKED (3-node setup with 1 arbiter)
Ravishankar N
ravishankar at redhat.com
Fri Oct 23 04:40:44 UTC 2015
On 10/21/2015 05:55 PM, Adrian Gruntkowski wrote:
> Hello,
>
> I'm trying to track down a problem with my setup (version 3.7.3 on
> Debian stable).
>
> I have a couple of volumes setup in 3-node configuration with 1 brick
> as an arbiter for each.
>
> There are 4 volumes set up in cross-over across 3 physical servers,
> like this:
>
>
>
> ------------------------------------->[ GigabitEthernet
> switch ]<--------------------------
> | ^
> |
> | |
> |
> V V
> V
> /-------------------------- \ /-------------------------- \
> /-------------------------- \
> | web-rep | | cluster-rep
> | | mail-rep |
> | | | |
> | |
> | vols: | | vols: |
> | vols: |
> | system_www1 | | system_www1
> | | system_www1(arbiter) |
> | data_www1 | | data_www1
> | | data_www1(arbiter) |
> | system_mail1(arbiter) | | system_mail1
> | | system_mail1 |
> | data_mail1(arbiter) | | data_mail1
> | | data_mail1 |
> \---------------------------/ \---------------------------/
> \---------------------------/
>
>
> Now, after a fresh boot-up, everything seems to be running fine.
> Then I start copying big files (KVM disk images) from local disk to
> gluster mounts.
> In the beginning it seems to be running fine (although iowait seems go
> so high that it clogs up io operations
> at some moments, but that's an issue for later). After some time the
> transfer freezes, then
> after some (long) time, it advances in a short burst to freeze again.
> Another interesting thing is that
> I see constant flow of the network traffic on interfaces dedicated to
> gluster, even when there's a "freeze".
>
> I have done "gluster volume statedump" at that time of transfer (file
> is copied from local disk on cluster-rep
> onto local mount of "system_www1" volume). I've observer a following
> section in the dump for cluster-rep node:
>
> [xlator.features.locks.system_www1-locks.inode]
> path=/images/101/vm-101-disk-1.qcow2
> mandatory=0
> inodelk-count=12
> lock-dump.domain.domain=system_www1-replicate-0:self-heal
> inodelk.inodelk[0](ACTIVE)=type=WRITE, whence=0, start=0, len=0, pid =
> 18446744073709551610, owner=c811600cd67f0000, client=0x7fbe100df280,
> connection-id=cluster-vm-3603-2015/10/21-10:35:54:596929-system_www1-client-0-0-0,
> granted at 2015-10-21 11:36:22
> lock-dump.domain.domain=system_www1-replicate-0
> inodelk.inodelk[0](ACTIVE)=type=WRITE, whence=0, start=2195849216,
> len=131072, pid = 18446744073709551610, owner=c811600cd67f0000,
> client=0x7fbe100df280,
> connection-id=cluster-vm-3603-2015/10/21-10:35:54:596929-system_www1-client-0-0-0,
> granted at 2015-10-21 11:37:45
> inodelk.inodelk[1](ACTIVE)=type=WRITE, whence=0,
> start=9223372036854775805, len=1, pid = 18446744073709551610,
> owner=c811600cd67f0000, client=0x7fbe100df280,
> connection-id=cluster-vm-3603-2015/10/21-10:35:54:596929-system_www1-client-0-0-0,
> granted at 2015-10-21 11:36:22
From the statedump, It looks like self-heal daemon had taken locks to
heal the file due to which the locks attempted by the client (mount) are
in blocked state.
In Arbiter volumes the client (mount) takes full locks (start=0, len=0)
for every write() as opposed to normal replica volumes which take range
locks (i.e. appropriate start,len values) for that write(). This is done
to avoid network split-brains.
So in normal replica volumes, clients can still write to a file while
heal is going on, as long as the offsets don't overlap. This is not the
case with arbiter volumes.
You can look at the client or glustershd logs to see if there are
messages that indicate healing of a file, something along the lines of
"Completed data selfheal on xxx"
> inodelk.inodelk[2](BLOCKED)=type=WRITE, whence=0, start=0, len=0, pid
> = 0, owner=c4fd2d78487f0000, client=0x7fbe100e1380,
> connection-id=cluster-vm-3846-2015/10/21-10:36:03:123909-system_www1-client-0-0-0,
> blocked at 2015-10-21 11:37:45
> inodelk.inodelk[3](BLOCKED)=type=WRITE, whence=0, start=0, len=0, pid
> = 0, owner=dc752e78487f0000, client=0x7fbe100e1380,
> connection-id=cluster-vm-3846-2015/10/21-10:36:03:123909-system_www1-client-0-0-0,
> blocked at 2015-10-21 11:37:45
> inodelk.inodelk[4](BLOCKED)=type=WRITE, whence=0, start=0, len=0, pid
> = 0, owner=34832e78487f0000, client=0x7fbe100e1380,
> connection-id=cluster-vm-3846-2015/10/21-10:36:03:123909-system_www1-client-0-0-0,
> blocked at 2015-10-21 11:37:45
> inodelk.inodelk[5](BLOCKED)=type=WRITE, whence=0, start=0, len=0, pid
> = 0, owner=d44d2e78487f0000, client=0x7fbe100e1380,
> connection-id=cluster-vm-3846-2015/10/21-10:36:03:123909-system_www1-client-0-0-0,
> blocked at 2015-10-21 11:37:45
> inodelk.inodelk[6](BLOCKED)=type=WRITE, whence=0, start=0, len=0, pid
> = 0, owner=306f2e78487f0000, client=0x7fbe100e1380,
> connection-id=cluster-vm-3846-2015/10/21-10:36:03:123909-system_www1-client-0-0-0,
> blocked at 2015-10-21 11:37:45
> inodelk.inodelk[7](BLOCKED)=type=WRITE, whence=0, start=0, len=0, pid
> = 0, owner=8c902e78487f0000, client=0x7fbe100e1380,
> connection-id=cluster-vm-3846-2015/10/21-10:36:03:123909-system_www1-client-0-0-0,
> blocked at 2015-10-21 11:37:45
> inodelk.inodelk[8](BLOCKED)=type=WRITE, whence=0, start=0, len=0, pid
> = 0, owner=782c2e78487f0000, client=0x7fbe100e1380,
> connection-id=cluster-vm-3846-2015/10/21-10:36:03:123909-system_www1-client-0-0-0,
> blocked at 2015-10-21 11:37:45
> inodelk.inodelk[9](BLOCKED)=type=WRITE, whence=0, start=0, len=0, pid
> = 0, owner=1c0b2e78487f0000, client=0x7fbe100e1380,
> connection-id=cluster-vm-3846-2015/10/21-10:36:03:123909-system_www1-client-0-0-0,
> blocked at 2015-10-21 11:37:45
> inodelk.inodelk[10](BLOCKED)=type=WRITE, whence=0, start=0, len=0, pid
> = 0, owner=24332e78487f0000, client=0x7fbe100e1380,
> connection-id=cluster-vm-3846-2015/10/21-10:36:03:123909-system_www1-client-0-0-0,
> blocked at 2015-10-21 11:37:45
>
> There seem to be multiple locks in BLOCKED state - which doesn't look
> normal to me. The other 2 nodes have
> only 2 ACTIVE locks at the same time.
>
> Below is "gluster volume info" output.
>
> # gluster volume info
>
> Volume Name: data_mail1
> Type: Replicate
> Volume ID: fc3259a1-ddcf-46e9-ae77-299aaad93b7c
> Status: Started
> Number of Bricks: 1 x 3 = 3
> Transport-type: tcp
> Bricks:
> Brick1: cluster-rep:/GFS/data/mail1
> Brick2: mail-rep:/GFS/data/mail1
> Brick3: web-rep:/GFS/data/mail1
> Options Reconfigured:
> performance.readdir-ahead: on
> cluster.quorum-count: 2
> cluster.quorum-type: fixed
> cluster.server-quorum-ratio: 51%
>
> Volume Name: data_www1
> Type: Replicate
> Volume ID: 0c37a337-dbe5-4e75-8010-94e068c02026
> Status: Started
> Number of Bricks: 1 x 3 = 3
> Transport-type: tcp
> Bricks:
> Brick1: cluster-rep:/GFS/data/www1
> Brick2: web-rep:/GFS/data/www1
> Brick3: mail-rep:/GFS/data/www1
> Options Reconfigured:
> performance.readdir-ahead: on
> cluster.quorum-type: fixed
> cluster.quorum-count: 2
> cluster.server-quorum-ratio: 51%
>
> Volume Name: system_mail1
> Type: Replicate
> Volume ID: 0568d985-9fa7-40a7-bead-298310622cb5
> Status: Started
> Number of Bricks: 1 x 3 = 3
> Transport-type: tcp
> Bricks:
> Brick1: cluster-rep:/GFS/system/mail1
> Brick2: mail-rep:/GFS/system/mail1
> Brick3: web-rep:/GFS/system/mail1
> Options Reconfigured:
> performance.readdir-ahead: on
> cluster.quorum-type: none
> cluster.quorum-count: 2
> cluster.server-quorum-ratio: 51%
>
> Volume Name: system_www1
> Type: Replicate
> Volume ID: 147636a2-5c15-4d9a-93c8-44d51252b124
> Status: Started
> Number of Bricks: 1 x 3 = 3
> Transport-type: tcp
> Bricks:
> Brick1: cluster-rep:/GFS/system/www1
> Brick2: web-rep:/GFS/system/www1
> Brick3: mail-rep:/GFS/system/www1
> Options Reconfigured:
> performance.readdir-ahead: on
> cluster.quorum-type: none
> cluster.quorum-count: 2
> cluster.server-quorum-ratio: 51%
>
> The issue does not occur when I get rid of 3rd arbiter brick.
What do you mean by 'getting rid of'? Killing the 3rd brick process of
the volume?
Regards,
Ravi
>
> If there's any additional information that is missing and I could
> provide, please let me know.
>
> Greetings,
> Adrian
>
>
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