IVM and powerpath

[ASERCO]

Hello all,
I have an IVM with version A.03.50.00 and configured 13 virtual machines into it. The cabinet is Clarion and we use powerpatch.
Few days ago we have a problem in a PCI target (fiber channel) and we lost the information on two guest because the disks assigned to these guests had this path. What happens with powerpath and IVM? On IVM we have configured 8 paths for earch device(disk) but we only assign one to each guest and isn't possible to assign more that one path to each guest.
What we can doy if we want solve this problem?
Best regards.

[Jeeshan]

Hi

Ask EMC about this problem and their findings. With the help of their findgs you will figure out what to do next.

[melvyn burnard]

if you are using Powerpath, surely you end up with ONE device file that refers to ALL paths? That is the device file you use to assign storage to a Virtual Machine Guest OS.
Virtual Machines will on use what you tell it, if you give it only one path, that is what it will use.

[Eric SAUBIGNAC]

Bonjour

EMC powerpath is supported with HPVM 3.5, so you should not have any trouble.

First I would do some controls at host level with something like "dd if=/dev/dsk/cXtYdZ" What happens when you disconnect one FC, then reconnect, then disconnect second one ? does the "dd" continues to works, or is there any IO error ?

Regards

Eric

[ASERCO]

Dear,

one example of the problem:

guest host
0/0/0/0.1.0 /dev/rdsk/c15t3d6
0/0/0/0.2.0 /dev/rdsk/c15t3d7
0/0/0/0.3.0 /dev/rdsk/c15t4d0
0/0/0/0.4.0 /dev/rdsk/c8t6d0

With powerpath we can see 8 ways for each disk but only one is configured at guest. If fails the FC that have the current hardware the guest that use tihs Hardware path loss the connection with the disk though at host we can see the disc by the other seven ways.

Best regards.

[Tim Nelson]

IMHO it is best practice to let the vHost take care of the failover and load balance of the backingstore .

I believe the HP IVM whitepaper supports this as well.

http://docs.hp.com/en/vse.html#HP%20Integrity%20Virtual%20Machines

[Eric SAUBIGNAC]

"With powerpath we can see 8 ways for each disk but only one is configured at guest."

--> That is a normal beahavior : you CAN'T have multipath in a VM guest. If you try to add a secondary path to a given LUN in a VM Guest, hpvmmodify will complain and refuse to do it

"If fails the FC that have the current hardware the guest that use tihs Hardware path loss the connection with the disk though at host we can see the disc by the other seven ways"

--> Have you done at host level the test I suggested in a previous post ? I guess that if the VM Guest losses the connection, the test will also fail at host level.

I don't know EMC powerpath but have some experience with other storage. So I think that your problem is probably due to the fact that you use native device file instead of EMC pseudo devices files.

Take a look at http://support.dell.com/support/edocs/stor-sys/powerpth/version4/uxinst.pdf (I know, it is a documentation for Solaris not for HP-UX !), page 5-5 "device naming" and try using pseudo devices instead of native ones.

Regards

Eric