Hi Rick In short: You're doing it right.
I recommend saving LUN ID 0 as a boot LUN if you think you ever want to boot from SAN.
The reason you can't have two LUN ID 0 on different igroups is because they are on the same target. The host/initiator has no idea about igroups. It's just a bunch of LUNs on a target WWPN.
Share and enjoy!
Peter
From: toasters-bounces@teaparty.net [mailto:toasters-bounces@teaparty.net] On Behalf Of rrhodes@firstenergycorp.com Sent: Wednesday, January 15, 2014 11:46 AM To: Toasters@teaparty.net Subject: igroup setup for a cluster
What's the best practice for setting up igroups and lun mapping for a cluster?
Last night we moved a cluster that uses luns on Netapp (IBM Nseries) to new servers. The old servers used internal boot disk, while the new use san boot.
I had it setup like this (names are different!): Igroup: serverA_boot wwnA1 wwnA2 boot_lun_mapped_in_lunid0 Igroup: serverB_boot wwnB1 wwnB2 boot_lun_mapped_in_lunid0 Igroup: cluster_luns all_the_cluster_luns_mapped_in_lunid0-149
During the cutover, I went to add all 4 wwn's (wwA1,wwnA2,wwnB1,wwnB2) into the cluster igroup. I was swinging the luns from the old server with internal boot to the new san boot servers and got an error. It complained that I couldn't put the new wwn's into the cluster igroup for luns because the boot igroups already had a lun id 0, and the cluster igroup also had a lun id 0. That is, the same wwn can't map to duplicate lun id addresses.
To fix, I simply remapped the cluster lun at id 0 to the next highest value, then I could add the wwn's and all was well.
Question: Is this the best way to create a san boot cluster? Is there a better way?
The next time I create a cluster lun It will be interesting what lun id gets assigned - lun id 0 (and get an error), or the next hightest.
I also thought of just mapping the cluster luns to both boot igroups, but like that a cluster lun igroup is kind of self documenting.
Thanks for any ideas!
Rick ________________________________
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