[DRBD-user] DRBD 9 auto-promote not changing role to Primary, but is writable

[Doug Cahill]

On Thu, Nov 14, 2019 at 4:52 AM Roland Kammerer <roland.kammerer at linbit.com>
wrote:

> On Wed, Nov 13, 2019 at 03:08:37PM -0500, Doug Cahill wrote:
> > I'm configuring a two node setup with drbd 9.0.20-1 on CentOS 7
> > (3.10.0-957.1.3.el7.x86_64) with a single resource backed by an SSDs.
> I've
> > explicitly enabled auto-promote in my resource configuration to use this
> > feature.
> >
> > The drbd device is being used in a single-primary configuration as a
> zpool
> > SLOG device.  The zpool is only ever imported on one node at a time and
> the
> > import is successful during cluster failover events between nodes.  I
> > confirmed through zdb that the zpool includes the configured drbd device
> > path.
> >
> > My concern is that the drbdadm status output shows the Role of the drbd
> > resource as "Secondary" on both sides.  The documentations reads that the
> > drbd resource will be auto promoted to primary when it is opened for
> > writing.
>
> But also demoted when closed (don't know if this happens in your
> scenario).
>
> > drbdadm status
> > r0 role:Secondary
> >   disk:UpToDate
> >   dccdx0 role:Secondary
> >     peer-disk:UpToDate
>
> Maybe it is closed and demoted again and you look at it at the wrong
> points in time? Better look into the syslog for role changes, or monitor
> with "drbdsetup events2 r0". Do you see switches to Primary there?
>

I checked the drbdadm status while my dd write session was in progress and
I see no change from Secondary to Primary.   I also checked the stats under
/sys/class and it looks the same.

cat /sys/kernel/debug/drbd/resources/r0/connections/dccdx0/0/proc_drbd
 0: cs:Established ro:Secondary/Secondary ds:UpToDate/UpToDate C r-----
    ns:3330728 nr:0 dw:20103080 dr:26292 al:131 bm:0 lo:0 pe:[0;0] ua:0
ap:[0;0] ep:1 wo:1 oos:0
resync: used:0/61 hits:64 misses:4 starving:0 locked:0 changed:2
act_log: used:0/1237 hits:28951 misses:536 starving:0 locked:0 changed:132
blocked on activity log: 0/0/0


> Best, rck
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