[DRBD-user] Problem setting DRBD device from Primary to Secondary

[Vigna, Juergen]

Hello List,

I have a strange problem and cannot point my finger on it maybe there is some good soul who can help me.

My Setup is 2 Server with a DRBD Version 8.3 there are 2 disks in HW- RAID1 an on the disk /dev/sda1 there
is a VolumeGroup defined. On the VolumeGroup I have a LogicalVolume /dev/vg00/lvdata and on this I defined
a DRBD Device with this configuration:

global { usage-count no; }
common {
    protocol C;
    syncer { rate 33M; al-extents 503; }
    startup { wfc-timeout 60; degr-wfc-timeout 50; }
    disk { on-io-error detach; }

    net {
       cram-hmac-alg sha1;
       shared-secret "Secret-Key";
       max-buffers 16000;
       max-epoch-size 16000;
       sndbuf-size 0;
       rcvbuf-size 0;
      #ko-count 6;
      #unplug-watermark 128;
    }
}

resource r0 {
    device    /dev/drbd0;
    disk      /dev/vg00/lvdata;
    meta-disk  internal;

    on neteye01 {
       address   192.168.0.1:7789;
    }
    on neteye02 {
       address   192.168.0.2:7789;
    }
}

This defines a /dev/drbd0 device on which I installed a ext3 filesystem and mount on /data path.

Now sometimes it happens that I have to move the mount to my other cluster node so I should do this
operatione:

umount /data
set drbd0 Secondary

while the first operation succeeds when I try to do the second: drbdsetup /dev/drbd0 secondary I get this error messages:

May 10 00:02:18 neteye01 kernel: block drbd0: State change failed: Device is held open by someone
May 10 00:02:18 neteye01 kernel: block drbd0:   state = { cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate r----- }
May 10 00:02:18 neteye01 kernel: block drbd0:  wanted = { cs:Connected ro:Secondary/Secondary ds:UpToDate/UpToDate r----- }

Eventually if I wait long enough the command succeeds but I need to be able to force the command to succeed or do something
to unlock it and make it secondary.

Now after this long introduction my question:

Can someone tell me *what* can still lock the device???

Kind regards,

    Jug

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