ESX Cluster with a mixed Path Selection policy of Fixed and Round Robin

[ksurya]

Hello All,

I have a task in hand to achieve on my running Virtual Infrastructure of ESX hosts on 4.0.2. This task is to change the default PSP from Fixed to Round Robin for my SATP(which is VMW_SATP_SYMM) which is the default SATP for EMC's Symmetrix V-Max arrays being used in my environment.

I have chalked out a plan to rollout the PSP changes on the ESX host. My concern is while i do it on my ESX cluster running production VMs, on one ESX host at a time since this change requires a reboot, is there something i need to be careful about the storage I/O, since while i do the changes i will have a situation where some ESX hosts will have FIxed policy and some will have the Round Robin policy for the path selection. Do u see any trouble in this before all ESX hosts have the same path selection policy after complete rollout?

Any Inputs from the community are appreciated.

Thanks,

Kartik S

[athlon_crazy]

No problem if you do it one host at a time. Make sure to clear the VMs first and switch on maintenance mode for that partiular host before you change the policy. You should be okay then.

[kgottleib]

I didn't know this requires a reboot, you should double check that... I'm working in ESX4.1 and it does NOT require a reboot to switch to RR.

[ksurya]

Yes, that is correct, you dont require a reboot if you change the PSP for a single datastore by getting into the properties for a datastore and then moving to the "manage paths" section and selecting the PSP as u may desire. I want to make a change to PSP for all datastores from fixed to RR and i do it by setting the default PSP for the SATP to RR using the following command.

"esxcli nmp satp -s VMW_SATP_SYMM -P VMW_PSP_RR".

After that i did check for the desired change to the PSP without a reboot first after executing the command above and checking using the following command.

esxcli nmp device list.

I even did a rescan of the HBA to check if the desired change is achieved. But i believe to set a default policy across the board for a SATP, you require a reboot of the ESX host. I am not aware if there is some advanced setting available to achieve this without a reboot. If there is any please let me know.

[MarekZdrojewski]

Hi,

Alternatively, you could change the policy through vCenter of vSphere Client. Rescan/refresh the datastore one by one and you should be fine. No reboot required through GUI.

hth

Marek.Z