Locking SAN Tape Drives

[Jack Trachtman]

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?

[Thomas Ritter]

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.

[Jack Trachtman]

Tom,

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

[Uwe Zessin]

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).

[Petr Spisek · Accepted solution]

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

[Tom O'Toole]

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).

[Jack Trachtman]

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.