EMC powerpath Vs hp-ux 11.31 multipathing

[paabhi]

Hi All,

Our new 11.31 servers are having 2 paths for disks.Storage using is EMC DMX4000.Customer is asking to use powerpath.Since native multipathing is available in 11.31, will powerpath gives any additional advantage.

Is there any known issues with 11.31 multipathing+EMC DMX storage

Abhilas

[Duncan Edmonstone]

It's really up to EMC to justify why the customer needs a 3rd party MPIO solution on an OS that has MPIO "built-in", I'm sure there will be some corner cases where using PP might make sense, but in general I would suggest its not necessary on 11.31.

One point to consider is that PowerPath on 11.31 uses the legacy DSFs (/dev/[r]/dsk) rather than the new agile DSFs (/dev/[r]disk), so you will have all the same IO stack limitations that you had in 11.11 and 11.23.

11.31 Native MPIO works great with DMX - the customer will need to be on a minimum firmware rev and have a couple of specific DMX director bits set for 11.31 which are different from 11.11/11.23, but it does work and work well...

HTH

Duncan

[paabhi]

Hi Duncan

Thanks for your reply.Please could you tell more about ""One point to consider is that PowerPath on 11.31 uses the legacy DSFs (/dev/[r]/dsk) rather than the new agile DSFs (/dev/[r]disk), so you will have all the same IO stack limitations that you had in 11.11 and 11.23."

Also do u have any info about the points to be crosschecked at storage level

Abhilash

[Duncan Edmonstone]

well basically you will have to manage disk in the same way you did on 11.11/11.23

- There will be a limit of 255 virtual buses supported - if you present a _lot_ of LUNs and they change regularly this gets difficult to manage
- If you change you SAN your disk device files (DSFs) will probably change
- You still have a disk device special file per path to the LUn rather than just one...

Basically all the features described in this WP are not available to you:

http://docs.hp.com/en/MassStorageStack/The_Next_Generation_Mass_Storage_Stack.pdf


HTH

Duncan