Can we have more than one alternate/pvlinks for a device???

[Geoff Wild]

You can have only 1 primary, but as many alternates as you have paths to.

Rgds...Geoff

[Caesar_3]

Hello!

Yes you can.

Caesar

[James R. Ferguson]

Hi:

Yes, up to eight (8) pv_paths to a single physical disk are supported. However, LVM will use only one at a time (the "primary" or first defined in '/etc/lvmtab').

Regards!

...JRF...

[Martin Johnson]

The question is: Why would you want to? The money could be better spent elsewhere. The links are pretty reliable. With over 200 servers, I've had only 1 fail in the last 5 years. The alterate worked fine. Except for the entries in the syslog, no one knew a thing.

HTH
Marty

[Jeff Schussele]

Hi Ila,

Yes, you can have up to 7 alt links.
But unless they are an *entirely* unique path to the LUN, it's pointless for either redundancy or load-balancing.

Rgds,
Jeff

[Steve Post]

Yes. In one case you MUST have it set up.

That case is for MC/Service Guard. I have two V-Class machines hooked to the same disks via 4 separate scsi channels....each.
I have the production volume group set up with one primary pv, and one alternate.

When I moved the volume group to the alternate node, it refused to import the volume group. Why? Because the alternate node wants to use one primary pv, and THREE alternates.

So, I had to set up the volume group with one PV and 3 alternate PV's for it to move correctly from one node to another.

just an fyi.

[Brian DelPizzo]

If you are using EMC powerpath, Veritas VM loadbalancing, or HP Autopath, you will have multiple paths between the host and a disk array. In this case it is in your interested and recommended by HP that you setup all of your alternate links. The reason is that if you do not, a disk may easily be accidentally overwritten. For example, your junior admin wants a blank disk and sees one not in a volume group. pvcreate -f and poof you are minus one production disk. I would create alt links in any situation where you have them visible.