topic Locking SAN Tape Drives in Operating System - OpenVMS

Locking SAN Tape Drives

Jack Trachtman — Thu, 09 Feb 2006 14:38:21 GMT

We have multiple VMS hosts connected through
an HP SAN to a shared HP tape-library.

Is there any way for a host to somehow
"lock" a drive for its own use, so that
when another host tries to Allocate the
device it will see the device as
unavailable?

Re: Locking SAN Tape Drives

Thomas Ritter — Thu, 09 Feb 2006 16:56:49 GMT

Just "$ alloc" the drive by it name. SLS for example works this way.
$ alloc on node and it will not be available on the other nodes.

Re: Locking SAN Tape Drives

Jack Trachtman — Thu, 09 Feb 2006 19:10:18 GMT

Tom,

$ ALLOCATE will work within nodes of a cluster. I'm looking for something that
works across unrelated hosts.

Re: Locking SAN Tape Drives

Uwe Zessin — Fri, 10 Feb 2006 02:12:23 GMT

The host would have to send a SCSI "RESERVE UNIT" command, but I have never heard that you can do that from 'vanilla VMS'. More complex backup software can even lock the entire library, so that the operator cannot manually open the door(s).

Re: Locking SAN Tape Drives

Petr Spisek — Fri, 10 Feb 2006 07:12:49 GMT

Hi,
way is to use Data Protector or MDMS (layer of ABS) to sharing allocate informations.
Petr

Re: Locking SAN Tape Drives

Tom O'Toole — Fri, 10 Feb 2006 11:38:57 GMT

Have you (or anybody) tried to see what happens when you try to allocate and use a drive that's already in use by another system? I have been meaning to try this, but haven't yet had the opportunity (that is: don't want to mess with the production systems that use these drives).

Re: Locking SAN Tape Drives

Jack Trachtman — Mon, 13 Feb 2006 16:20:47 GMT

Tom,

Unfortunately we have seen what happens
when tape-drive usage isn't coordinated across hosts - we had one host tell the jukebox to grab a tape from one drive (being used on another host) and put it in another drive. The first host wound up with a hung device and we had to boot to free it.