[DRBD-user] Primary/Primary mode permanent error

[Андрей Коновалов]

Hello!

I have permanent troubles with Primary/Primary mode: nodes disconnected and split-brained after 5-10 minutes running in this mode.

Message was written to log when we are switching role from Secondary to Primary:
May 31 19:02:57 ve1 kernel: block drbd1: role( Secondary -> Primary )
At the moment of switching from primary/primary to primary/unknown i see in /var/log/messages something like this:
May 31 19:10:03 ve1 kernel: block drbd1: peer( Primary -> Unknown ) conn( Connected -> ProtocolError ) pdsk( UpToDate -> DUnknown )

My config for /dev/drbd1 is:
ve1:~# sed -rn '/^resource\s+vm-101-disk-1\s*\{/,/^\}/p' /etc/drbd.conf
resource vm-101-disk-1 {
        protocol C;

        handlers {
                pri-on-incon-degr "echo 'DRBD: primary requested but inconsistent!' | wall; /etc/init.d/heartbeat stop";
                pri-lost-after-sb "echo 'DRBD: primary requested but lost!' | wall; /etc/init.d/heartbeat stop";
        }

        startup {
                wfc-timeout  15;
                degr-wfc-timeout 60;
        }

        net {
                timeout 120;
                connect-int 20;
                ping-int 20;
                max-buffers     2048;
                max-epoch-size  2048;
                ko-count 30;

                cram-hmac-alg sha1;
                shared-secret "vm-101-disk-1";

                data-integrity-alg crc32c;

                allow-two-primaries;

                after-sb-0pri discard-zero-changes;
                after-sb-1pri consensus;
                after-sb-2pri consensus;
        }

        disk {
                on-io-error   detach;
        }

        device /dev/drbd1;
        disk /dev/replicated/vm-101-disk-1;
        meta-disk internal;

        on ve1 { address 192.168.77.1:7701; }
        on ve2 { address 192.168.77.2:7701; }
}

DRBD module info:
ve1:~# modinfo drbd
filename:       /lib/modules/2.6.33/kernel/drivers/block/drbd/drbd.ko
alias:          block-major-147-*
license:        GPL
version:        8.3.7
description:    drbd - Distributed Replicated Block Device v8.3.7
author:         Philipp Reisner <phil at linbit.com>, Lars Ellenberg <lars at linbit.com>
srcversion:     EE47D8BF18AC166BE219757
depends:        lru_cache
vermagic:       2.6.33 SMP mod_unload modversions
parm:           minor_count:Maximum number of drbd devices (1-255) (uint)
parm:           disable_sendpage:bool
parm:           allow_oos:DONT USE! (bool)
parm:           cn_idx:uint
parm:           proc_details:int
parm:           usermode_helper:string

DRBD tools version:
ve1:~# drbdadm | fgrep Version
Version: 8.3.7 (api:88)

Kernel:
ve1:~# uname -rv
2.6.33 #1 SMP Fri Mar 5 14:04:53 MSK 2010

And here is my question: 
How can i get some more debug info, which could be helpful to solve this problem? :)
"Connected -> ProtocolError" in logs dont ask me anything!