When VxVM snapshots fail

So, I was casually using the snapshot function of Vertias Volume Manager (VxVM) the other day and learned something new. Let me tell you about it!

If you don’t know about them, VxVM snapshots allow you to create a temporary mirror of a volume’s primary data plex, the idea being that it’s going to be split off into separate volume later on. This is useful when used in combination with vxdg split — effectively allowing you to clone a disk group with very little effort (as long as you have the disk space!).

You need a Storage Foundation Enterprise license to use the vxdg split functionality. But in practice, the workflow looks like:

[embed]Surprisingly simple, and can be done with multiple volumes, too.

Now, you have a new disk group containing a copy of your source volume. The disk group has a new disk group ID too, so there’s no fear of clashing. Both can reside happily on the same host, imported simultaneously.

However, I came across a gotcha when performing the snapshot operation:

[embed]Oh boy. Thanks for the useful error message!

No amount of searching Symantec’s documentation could shed light on this. The error message was obscure and didn’t seem to point me in any particular direction.

Thankfully, one of my colleagues (thanks, Susan W.!) pointed out the following little known piece of information regarding VxVM volumes:

Disk group and volume names can only contain up to 31 characters.

Huh. Let’s see…

[embed]How ‘bout that?

Argh. My _new suffix had put me over the line! After changing my target volume name to something with fewer characters, everything worked as expected.