DLT Tape Library Model 4155w, configuring 2 servers to use Tape Library

[CA796084]

Has anyone had any luck with putting 2 Servers onto this type of Tape Library. We are using SCO Openserver 5.0.6 as the O/S and Microlite BackupEdge 01.01.08 as our backup software.
Both servers have the loading and unloading tape functionality, I can backup one one server with no problems. When I try to run a backup on the second server the backup hangs, eventually the I get a message SCSI tape 0 device 46/0 offline. Backup would be performed at different time, so there is no conflict there. Looking for what SCSI cable setup that is needed for this, manaul does not really spell it out concerning 2 servers.

Thanks,
Bill Osness - Manpower Intl.

[BR19682]

Hi there.
What we have done here :
config one server as backup master
connected with a separate network connection to second server
using this second connection to backup second server as network file system
Rgds
Alexander M. Ermes

[Rothery Harris]

Dear Bill,

The DLT tape drive and indeed the library cannot support what is known as multi-initiator SCSI. This is where there are 2 HBAs communicating with one peripheral. The SCSI standard does support multi-initiator working but the tape drives must be able to cope.
Connect one server to the library and backup the other server 'over the network'.

Rothery Harris

[CA814553]

Hello Bill,

OmniServe from TD Systems solves the "Multi-initiator" problems. Check at www.tdsys.com.

Peter Brewster

[Curtis Ballard]

I can't find any mention of a DLT tape library 4155 so am not certain exactly what device that is. However when overlapped commands are not being sent any SCSI device should be able to run with 2 hosts on the same bus unless one or both of the servers tries to scan the bus. For example Windows 2000 or XP will scan the bus in the background unless manually configured to not scan, and will have fits if somebody else is using a device on it's bus.

If you are absolutely certain that the backups will not ever overlap and that your OS is not doing background scanning then you can run with 2 servers connected without problem. You will have to manually enforce no overlaps though so it can be an administrative headache. The main thing to check is to make certain that the servers are using different host ID's. If there is an ID conflict usually neither will work but sometimes one server is enough faster that it will always respond first and will work ok.