Migrate single-hosts-exports to host-set exports

[khblenk]

Hello,

I've got a lot of virtual volumes exported to 3 single hosts directly (3 exports). I want to switch this exports to a host-set containing this 3 (or in future 4) hosts. I've created the new host-set.

How can I change the exports from 3 exports ("Host sees") to 1 export ("Host in Set") "automaticaly" (=by script/CLI)? And if I do this, will the LUN be offline a short time or can I make this changes while the hosts are online without interruption (virtual machines on the VVs)?

Kind regards,
Karl-Heinz

[Richard Siemers]

Great question, I am interested in what the optimal method will be as well. I am unaware of a hot/online fix for this... the process I would use would be put one of the cluster nodes in maintenance mode (offline), delete its specific VLUN templates, then export the VVset to the host. Bring host back online... validate, bring next host down for maintenence, etc etc..

[BryanW]

A host can have multiple exports from the same vv.
Why not just create a host set, add the hosts and export the volume set to it.
Then wait until you are sure it sees the new export and remove the direct exports leaving only the group export.
This should not delete the VLUNs, you should see the exports as "host in set" and any future exports will be done via the host set.

I would try it with some test VVs first, but I don't see why this shouldn't be an online process.

Bryan @Match.con

[Richard Siemers]

Definitely needs a test. My concern was that it would not let you export the same VV twice with the same LUN number, and I was assuming the desired result would be to maintain existing LUN mappings in the conversion.

[Davidkn]

A host can have multiple exports from the same vv.
Why not just create a host set, add the hosts and export the volume set to it.
Then wait until you are sure it sees the new export and remove the direct exports leaving only the group export.
This should not delete the VLUNs, you should see the exports as "host in set" and any future exports will be done via the host set.

I would try it with some test VVs first, but I don't see why this shouldn't be an online process.

Bryan @Match.con

This is what I would do too, as in theory, as long as e host set is right, then the final removal of the single vluns should leave the working host set so the host should not notice any change.

[BryanW]

I guess this all depends on how your host reacts to VLUN IDs changing, so I would definitely test it in your environment.

I was able to simulate this online with a Windows 2008 R2 host by exporting a test VV directly to the host which created VLUN 0, then adding the host to a group and exporting to it - which created VLUN 1. I deleted VLUN 0 and the LUN now shows exported as host in set as VLUN 1. I selected just the VLUN 0 by using the Active VLUN tab under the host and selecting Unexport Volume for VLUN ID 0 - if you do it at the VV level it will try to unexport both VLUN IDs and the host would lose access.

I didn't see any impact to VV access during my test, but again I would try it out with your hosts.

Bryan @ Match.com

[Richard Siemers]

Interesting, so the secret sauce must be MPIO? I assume MPIO intelligently recognized the new LUN# as an existing device and just added its new path to the config for existing volume?

[BryanW]

MPIO and or the Host OS's recognition of the disk device by NAA/EUI as unique