[DRBD-user] What is exact moment of split brain?

[himanshu padmanabhi]

Here's my drbd.conf

resource "res1" {
        protocol C;
        startup {
                wfc-timeout     0;
                degr-wfc-timeout        120;
        }
        disk {
                on-io-error     detach;
        }
        net {
                allow-two-primaries;
        }
        syncer {
                rate 15M;
        }
        on "machine1systems.com"
        {
                device  /dev/drbd0;
                disk    /dev/sdd;
                address 192.168.30.12:7788;
                meta-disk       internal;
        }
        on "machine2.systems.com"
        {
                device  /dev/drbd0;
                disk    /dev/sde;
                address 192.168.30.14:7788;
                meta-disk       internal;
        }
}

service drbd start
drbdadm adjust res1(on both sides)
drbdadm primary res1(on both sides)

Then *on local primary side*,
pvcreate /dev/drbd0
vgcreate drbdtest /dev/drbd0
lvcreate -n drbdlv1 -L 50M drbdtest

Then,on *remote primary side*,I took snapshot
lvcreate -S -n snap_drbdlv1 -L 50M /dev/drbdtest/drbdlv1

I am using 'drbd-8.3.0' on 'CentOS 2.6.18-92.el5' machines.

*My problem*
I tested above similar scenarios like above,I got split brain error at
different intervals.

like first time I got it after 10 minutes,so using
http://www.drbd.org/users-guide/s-resolve-split-brain.html,I recovered from
it.

Then when I tested I got split brain after 30 minutes(though no operation
was going on @ that time,I am closely watching /var/log/messages),then after
recovery I got it after 1 hour and so on.

So I am totally confused @ exact event of split brain.Though I am doing any
IO,I got it sometimes.
I am not using any shared file system at the moment.It might be required
only if I want that level of concurrency.
---------------------------------
Thanks and Regards,
Himanshu Padmanabhi
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