Best practices for doing disk work on DS4500 SAN & HP

[Dan Deck]

We have several HP11.11 servers attached to a IBM DS4500 SAN. We have found that as our DS4500 gets more and more disk and more work to do, we have had to adopt some rather unconventional measures to ensure that we can keep the SAN controllers from flipping the connection to the alternate links and back again.
This is because we are using LVM/SLVM and this SAN only supports ACTIVE/PASSIVE links.

Does anyone have this same situation and what do you do for some of the activities?

lvextend:
If there are more than one lvextend to do in a vg we will vgreduce out the alt link(s) and then perform the lvextend(s) and after we are done we will vgextend them back in.

Rebooting serves:
We have also found that on rebooting a server we have to vgreduce all vg's attached to the SAN and then vgextend them back in after the system comes up.

In a SLVM where the disk is active shared in SG cluster we have to do the usual things like vgchange -c y -S n vg_name then do the work. But I also vgreduce out the alt links to do the work and then vgextend them back in.
I have also found that when importing the vg on the other system using vgimport we use the -f and specify only the primary links in the file so that the import goes without a hitch. I have found the if you use the -s in vgimport lvm will probe all attached disks and cause even more controller link flipping.

ServiceGuard Failover:
We really haven't figured out what might be the best thing to do here!

Now the bad side to all this is that we still take a bit of a hit when we do the vgextend, but it is more manageable when we can see how our DS4500 is reacting and can do it in a controlled manner.

Anyone have this type of situation? We are going to replace this SAN but in the mean time we have to live with it.

[Steven E. Protter]

Shalom,

I think your last line identifies best practice.

The peformance of this device and its drivers for HP-UX is unacceptable. It should be replaces ASAP. I would not trust it with a backup of a backup of a backup.

Who knows what else it will do under stress.

SEP