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FC60 - How to change LUN-Channel assignment

Francesco Campalastri
Frequent Advisor

FC60 - How to change LUN-Channel assignment

Hi friends,
I found a LVM volume group on 5 LUN onto a FC60.
Every LUN has been assigned to Channel A.

Due to performance reasons may I change channel assignment to a couple of LUN without destroy them?

Thank in advance
Francesco
3 REPLIES
Julian Perez_1
Valued Contributor

Re: FC60 - How to change LUN-Channel assignment

Hello,

Did you mean that all LUNs are throught controller A?

If this is the case, you can manage your LUNs using LVM. LVM has priority over hard configuration, so you can use pvchange command in order to balance your LUNs, without any hard change.

Best regards,

Julian
Keep the faith
Francesco Campalastri
Frequent Advisor

Re: FC60 - How to change LUN-Channel assignment

What do you mean, Julianwith "LVM has priority over hard configuration"?

I know that using pvchange you tell to OS to use channel B but I think I force FC60 to do something like an internal routing.

I think that it will not be the best performance configuration.


Francesco
Julian Perez_1
Valued Contributor

Re: FC60 - How to change LUN-Channel assignment

Hi,

Service manual says that there are 2 I/O paths to each LUN on the disk array - one through controller A and one through controller B. LVM is used to establish the primary path and the alternate one to a LUN. The primary becomes the path for all host I/O to that LUN.

The first time an I/O is performed to the LUN using the alternative path, the disk array switches ownership of the LUN to the controller on the alternate path.

The primary path established using LVM defines the owning controller for the LUN. This may override the controller ownership defined when the LUN was bound.

For example, if controller A was identified as the owning controller when the LUN was bound, and LVM established the primary path to the LUN using controller B, controller B becomes the owning controller.


Best regards,

Julian
Keep the faith