TOPIC:

We have HA Lizard running on a 2 Host XEN environment. We need to replace the fiber NIC that the iscsi connection uses. Normal process forget UUID of old, scan and introduce new nic UUID. Will everything come back up for HA lizard or do we need to rebuild the connection if the UUID changes? I believe we should be able to keep the same interface name. Should we be able to have data retention as long as we follow normal maintenance procedures of disabling ha-cfg and setting iscsi-cfg to manual before we swap nic?

Hello Mike,
As long as the interface name remains the same and you configure the same replication IP on it, it should just work.
The only data we drive from to manage the floating IP and the shared storage is the interface name. You can see this configured in /etc/iscsi-ha/iscsi-ha.conf. The parameter is "DRBD_INTERFACE" and will be set to something like xap1, xenbr1, etc.. (matching whatever xenserver has named the interface). So, in answer to your question, yes the UUID will change, but it is transparent to us as we do not link to it.

The general steps for this procedure would be:

1) disable HA for the pool
2) Migrate all your VMs to the host that will remain running

3) Manual Mode (only if master is getting the new NIC)
If the master is the host you will be working on then you will need to go into manual mode and promote the slave to expose the storage
If the slave is the host you will be working on you can skip going into manual mode.

on master
on slave
4) shutdown host and replace nic.

If replacing the NIC on both hosts, do I just disable HA for the pool and set iscsi in manual mode, then shut down both hosts and swap NICs and rebuild adapters in XEN or do I need to do 1 host at a time and move primary/secondary back and forth having secondary be the 1 host we are swapping at that time?