[DRBD-user] Trouble with DRBD 0.7 - disappearing data

[Lukas Pecha]

Hello,
I have a strange problem with DRBD 0.7. I am using it to replicate some 
lvm volumes (which contains virtual machines for Xen) and it works fine. 
But one of the devices, the largest one (size about 50 GB, the others 
have only about 4-8 GB), is behaving strangely - here is an example of 
what I mean: I attach it to the virtual machine. That is okay, I have 
full read/write access etc. So I create some partitions on it and 
filesystems. Still okay. But when I try to mount the partitions, they 
are not there! One moment, it's all here, but a few seconds (or minutes) 
later is the whole disk empty, with no partitions at all! I tried it a 
few times, I have doublechecked and reloaded the configuration, the only 
thing I haven't done is reloading the whole servers and complete restart 
of drbd (but I will try it in the evening).

Do you have any idea why it is happening?
Thanks,
Luke


PS:
Here is part of my drbd.conf, with configuration of that troubling disk:

global {
    minor-count 14;
}

resource data_disk {
  protocol C;
  incon-degr-cmd "echo '!DRBD! pri on incon-degr' | wall ; sleep 60 ; 
halt -f";
  startup {
    wfc-timeout         0;  ## Infinite!
    degr-wfc-timeout   60;  ## 2 minutes.
  }
  disk {
    on-io-error detach;
  }
  net {
    # timeout           60;
    # connect-int       10;
    # ping-int          10;
    # max-buffers     2048;
    # max-epoch-size  2048;
  }
  syncer {
    rate   20M;
    group   9;
    al-extents 257;
  }

  on node1 {
    device      /dev/drbd8;
    disk        /dev/domains/data_disk;
    address     192.168.1.1:7797;
    meta-disk   /dev/domains/meta_drbd[8];
  }

  on node2 {
    device     /dev/drbd8;
    disk       /dev/domains/data_disk;
    address    192.168.1.2:7797;
    meta-disk  /dev/domains/meta_drbd[8];
  }
}