[DRBD-user] StandAlone->Primary/Unknown & StandAlone->Secondary/Unknown

Shane Walton dsrelist at yahoo.com
Thu Mar 31 16:44:31 CEST 2005


Hello,

Consider the following hardware configuration:

Node A connects to Node B by a switched network and
Node A connects to Node B by a crossover cable.

Consider the following software configuration:

DRBD communicates over the switched network and
Heartbeat (HA) communicates over both networks.

Now, following these steps I can repeat the case where
I have both nodes in a standalone state which requires
user intervention to reconnect the current PRIMARY
DRBD node.

1.) Node A is DRBD Primary and Node B is DRBD
Secondary
2.) I pull the switched network cable from node A
3.) Node A detects the failure and HA moves the
resources to node B
4.) Node B is now StandAlone->Primary/Unknown and node
A is StandAlone->Secondary/Unknown
5.) I reboot node A simulating a NIC replacement and
reconnect the switched network cable
6.) Node B aborts the node A DRBD connection
complaining that current Primary would be sync TARGET!
7.) Node A waits on a degraded connection timeout
forcing the need to run `drbdadm connect all` on node
B

I have read through previous posts and have seen this
issue mentioned a couple of times with responses
suggesting to ensure the DRBD net::timeout value is
lower than the HA deadtime and other suggestions to
configure DRBD over the crossover cable.

The timeout change did not make any difference.

Utilizing the crossover cable adds complications, such
as if one of the NICs break utilizing the crossover
cable, assuming the cable doesn't go bad, there is
data loss deciding which node has a bad NIC.

The best base would be for the secondary node to have
the bad NIC as it could sync up later.  If it is the
primary node, HA would have to move resource to the
secondary node ignoring the fact that there is data on
the primary node that did not get copied to the other
node.

So my question, is this the expected behavior of DRBD?

I appreciate your help with this matter and look
forward to your reply.

Regards,

Shane M. Walton


		
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