lars.ellenberg at linbit
Feb 20, 2012, 12:04 PM
Post #2 of 2
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On Fri, Feb 17, 2012 at 11:15:45AM +0200, Lawrence Strydom wrote:
> Hi List,
>
> I used DRBD in dual primary mode with ocfs2 for my load balancing
If you use dual primary DRBD with cluster file systems,
you *MUST* have *working* and *tested* fencing in place.
That is DRBD fencing policy has to be "resource-and-stonith",
and the "fence-peer" handler is supposed to trigger, or at least wait
for, a node-fencing as well.
This is necessary because otherwise, as soon as the replication
connection breaks, the data on both nodes could diverge.
(aka split brain, or even just resource-internal split brain).
I also recommend to upgrade to 8.3.12.
With 8.3.7, you'd probably still have to configure after-split-brain
auto recovery policies, even if you got the fencing right.
> web server cluster. I didn't encounter any errors during setup and
> when I put the web site on the DRBD device on the primary node, it
> replicated without any errors. It has been running fine during the
> week of testing but this morning when we updated code located on the
> DRBD device we noticed it was not replicating to the secondary node.
> the DRBD device was mounted on both nodes but /proc/drbd output this:
>
> *version: 8.3.7 (api:88/proto:86-91)
> GIT-hash: ea9e28dbff98e331a62bcbcc63a6135808fe2917 build by
> root [at] web01, 2012-01-10 09:54:40
> 0: cs:StandAlone ro:Primary/Unknown ds:UpToDate/DUnknown r----
> ns:0 nr:0 dw:5960937 dr:5047235 al:1490 bm:1363 lo:0 pe:0 ua:0
> ap:0 ep:1 wo:b oos:8840028*
>
>
> I restarted drbd and ocfs2 but still the result was the same. Next I
> rebooted the misbehaving node and noticed when it came back up that
> the DRBD device was no longer mounted.
>
> Trying to mount the device manually returns this error:
> *mount /dev/drbd0
> mount.ocfs2: I/O error on channel while opening device /dev/drbd0*
>
>
> A tail of the log file shows nothing but an earlier entry shows this:
>
> *Feb 17 10:47:54 web02 kernel: [ 13.531600] block drbd0: disk(
> Attaching -> UpToDate )
> Feb 17 10:47:54 web02 kernel: [ 13.535865] block drbd0: conn(
> StandAlone -> Unconnected )
> Feb 17 10:47:54 web02 kernel: [ 13.535889] block drbd0: Starting
> receiver thread (from drbd0_worker [1484])
> Feb 17 10:47:54 web02 kernel: [ 13.535998] block drbd0: receiver
> (re)started
> Feb 17 10:47:54 web02 kernel: [ 13.536006] block drbd0: conn(
> Unconnected -> WFConnection )
>
>
> *This is my r1.res file:
>
> *===============================================================
> resource r1 {
> meta-disk internal;
> device /dev/drbd0;
> disk /dev/vol01/docroot;
>
> syncer { rate 1000M; }
> net {
> allow-two-primaries;
> after-sb-0pri discard-zero-changes;
> after-sb-1pri discard-secondary;
> after-sb-2pri disconnect;
> }
> startup { become-primary-on both; }
>
> on web01.junkmail.co.za { address 10.0.0.111:7789; }
> on web02.junkmail.co.za { address 10.0.0.112:7789; }
> }*
> *===============================================================*
>
>
>
> Here is /etc/ocfs2/cluster.conf:
>
> ===============================================================
> *cluster:
> node_count = 2
> name = jbm_web
>
> node:
> ip_port = 7777
> ip_address = 10.0.0.111
> number = 1
> name = web01
> cluster = jbm_web
>
> node:
> ip_port = 7777
> ip_address = 10.0.0.112
> number = 2
> name = web02
> cluster = jbm_web
> ================================================================
>
>
>
> *Any help/ideas much appreciated - the pressure is on here.
>
> Thanks
> *
>
>
>
> *
> *-- *
> *Lawrence Strydom*
> *Linux System Administrator*
> Junk Mail Publishing Group
> Tel : (+27) 12 342 3840 Ext 2811
> Fax : 0000
> Email : lawrence [at] junkmail
>
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--
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com
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