ESX by default is set to use fixed paths for default lun multipathing. I thought this would be interesting post with my growing use of Netapp.
For a more “plug-n-play” architecture an ESX deployment can enable ALUA on the Netapp Storage Array and configure Round Robin multipathing.
Enabling ALUA in Netapp
*ALUA is only supported in Netapp 7.3.1.1 Data On Tap and Higher
Below are the steps to ensure success:
How can I set my igroup to Alua?
1) Login to Netapp Console
2) igroup set <igroup name> alua yes (for each ESX4.x lun)
How can I verify that my igroup has been configured for ALUA?
igroup show -v <igroup-name>
Note in the situation of upgrading non-alua to alua luns post enabling alua on the igroups you need to reboot the host.
How can I set my PSP (path selection policy in Vsphere to RoundRobin?
Two ways (maybe more):
1) On the ESX Host from console run (to set defaults)
esxcli nmp satp setdefault -psp VMW_PSP_RR -satp VMW_SATP_ALUA
2) Select an ESX server -> Configuration Tab->select storage adapters->selet HBA->”highlight all luns” then right click select manage paths then multipathing policy and perferred path (Round Robin)
3) SVC2.0 Storage Virtualization Console will set this configuration automatically if you provide a discovery and then have it apply its recommendation
Are there any Gotchas?
Yes, Two Situations
1) An ESX 4.0 host is presented to a 3.5 host (this situation is common in our environment) use fixed path till post migration. Then switch to round robin on the ESX side and Netapp side
2) If you have VMs running MSCS are not supported with the RR PSP.
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