migration from iSCSI single to iSCSI multipath

[GandR]

After a recent SAN issue, it has been recommended that our cluster should be using multipath. In preparation, I installed the various software modules using apt-get but didn't realise that the installation would start the services. I have shutdown and disabled them but now seem to be stuck. All the VM disks are visible on two disks. I can't migrate or backup anything.

I am prepared to shutdown all of the VMs on a node and reboot it to try to get back to the system seeing only the single iSCSI mount but if that is successful, how do I move to multipath in a live cluster ? All the documentation seems to relate to installing multipath storage as part of the initial build.

I am still running 5.0-30, upgrading to 6 is scheduled to occur shortly but currently I cant migrate any VMs between hosts to allow me to do the upgrade. Presenting the LUN via two paths hasnt yet happened as it involves adding to the network configuration, which typically requires a reboot of each node.

Any assistance would be very appreciated. Thanks in advance.

 

[alexskysilk]

its a relatively simple matter of
1. bring up your second interface.
2. install and configure mpio.
3. edit your iscsi targets and replace the disks with their mpio counterpart.
3. filter out /dev/sd* from lvm.conf
4. reboot. cluster should remain unaffected as the actual lvm is the same.

I assume you got as far as step 2. this tutorial may be of help: https://elkano.org/blog/set-up-multipath-iscsi-targets-on-debian/

 

[GandR]

Thank you, I'll have a look at that tutorial.
Is there any easy way to resolve the error with the VMs appearing on two devices without rebooting?

 

[alexskysilk]

It is theoretically possible to do all the above without reboot, but it would necessitate moving all your vms to other nodes first (in which case you can reboot safely anyway)