[DRBD-user] Remove network cable causing system reboot

Digimer linux at alteeve.com
Tue Aug 16 18:55:28 CEST 2011

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On 08/16/2011 12:43 PM, Louis Voo wrote:
> Hi,
> I've 2 xen server setup using DRBD. The VM is run on the DRBD partition. 
> Both server running on Centos 5.6 with 2 NIC, 1 NIC is use by DRBD
> direct connect to another server using cross over cable. One run on
> Primary mode and another run on Secondary Mode.
> Everything work fine so far, but we just found that when the VM is
> running and if we remove the cross over cable, the primary host will get
> reboot.
> Is it something to do to DRBD setup?

Doesn't look like it, as you've not configured fencing. Are you running
a cluster proper? If so, what? If you do, and if that cluster is using
the DRBD link for cluster communication then breaking the link could be
triggering the cluster's fencing.

A couple of comments:

>         net {
>                 allow-two-primaries;                 
>                 cram-hmac-alg sha1;
>                 shared-secret "123456";

You're on a dedicated link, so there is no real reason to add the
overhead of encryption.

Secondly, whenever you have dual-primary, you *must* have fencing
configured. In EL5/DRBD 8.3.9 this is done with:

        disk {
                fencing         resource-and-stonith;
        handlers {
                outdate-peer    "/sbin/obliterate-peer.sh";

Replace that script if you're not using red hat cluster service with a
script that will call the fence device of your choice.

E-Mail:              digimer at alteeve.com
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