how to use and create pvlink

[Morten Kristiansen]

Hi,

we are going to attatch an EMC Clariion to a HP-UX L2000 server with a fiber HBA. I've been told that we're gonna see the disks assigned from the Clariion twice and to use pvlink. I've never used pvlink and have browsed this forum and searched the google, but none have given me a exact answer how to create and use pvlink.

I've also read the man page for vgcreate. There it says that you only define both pvpaths in the vgcreate command and the pvpath mentioned first will be the primary path. Is it that simple? Or am I missing something?

I have to be shure before we connect to the Clariion because we're gonna move some filesystems to the Clariion and therefore I have no time to loose in trying and failing.

Thanks in advance.

[DCE]

It is indeed that simple. The first path referenced with the vgcreate/vgextend is the primary path, and the second path is the fail ocer connection. When you issue a vgdisplay -v command, it will show the links

Dave

[Don Wilt]

Morten,
It is that simple... when you add the second pv it will show up as an alternate and will be listed below the primary path. I also like to alternate primary paths to try and balance the i/o, unless you are using EMC PowerPath.

[Morten Kristiansen]

So is it preferable to use powerpath instead of pvlink? What are the pros and cons about using powerpath versus pvlink?

I also saw in another posting about pvlink that there where some parameters to tune on. Where do I find these. Here are two parameters that's important to a failover situation:

Linkdown-tmo was set to 60 and no_device_delay was set to 30.

[Don Wilt]

PowerPath will perform i/o tuning automatically, if the first channel is busy it will direct the i/o down the alternate path. Pvlink is a manaul tuning... PowerPath is a seperate product and would need to purchased from EMC.