Should I specify alt path in VG on a clarion if I have powerpath?

[Jay_122]

Hi,
I have a CX3-40 that I am setting up on our HP Itanium servers running HP/UX 11.23. I would like to know if I need to specify an alt path in my VG's if I am running powerpath. I've read the EMC powerlink articles and some say to only put in 1 alt path and some say not to. Which is correct? All help is appreciated.

[Duncan Edmonstone]

Jay,

I can't remember the exact details, but I seem to recall it depends on how you have trespassing set up for a given LUN on the CX.

If it is setup to fail-over a LUN straight away if the alternate link is trespassed, then no - don't use PVlinks.

If its not setup like that, then you can use PVlinks.

HTH

Duncan

[Tim Nelson]

Using PowerPath or SecurePath the alt link really does not matter as both these products put themselves in front of the real io driver. A reference to a dead path would be automatically routed to a live one.

The only case in question is during boot. When does PP or SP become enabled, before or after vg activation ?

I have only used active/active arrays so I did not have to worry and just put the alt link in the vg to CYA.

If you have a test server.
-configure the vg with one path.
-unplug that path and reboot.
-did the vg activate after boot ?
-if so then there is absolutely no need for the alt link to be in the vg config.

One note. In some cases it may be nice to have it in the vg so you can quickly see what paths belong to where..

[Tim Nelson]

One other quick note.

11.31 includes mulitpath management.

This will eventually obsolete PowerPath and Secure Path.

If you had a choice, save all that PowerPath money and install 11.31.