make_tape_recovery

[chad_c]

Hi. We are running HPUX 11.11. We would like to make a backup to a tape. However, when we plug our scssi hp surestore dat 40 into our server, the server locks up. The spare scsi ports on the workstation and the tape drive are both terminated with scsi plugs.

Can anyone shed some light on why when we turn the tape drive on, it locks up our hpux 11.11 workstation?

Regards,
Chad

[A. Clay Stephenson · Accepted solution]

The most likely problem is that your have a SCSI ID conflict. (ie, more than one device on the same SCSI bus having the same ID)

[Matti_Kurkela]

Which model of a HP server/workstation it is?
(What does the "model" command say?)

You say "when you plug in the tape drive, the system locks up". This suggests you're connecting the cables while the system is running. This is not supported nor recommended. Some models have separate SCSI controller(s) for the external connectors: with these you might get away with hot-plugging things, although it is still not recommended.

Workstations may have the external SCSI connector on the same SCSI bus with the internal system disks: hot-plugging SCSI cables on these systems will disrupt the access to the system disks. The disruption may cause just some lbolt errors appearing in the system log, or it may crash the system if you're unlucky.

Not all SCSI is equal: there are several kinds of SCSI devices: Single-Ended (usually identified with a SE label), High-Voltage Differential (currently identified with "HVD", originally with just "DF") and Low-Voltage Differential (LVD).
If you see a SCSI interface marked "DF", it actually means HVD, never LVD.

HP Surestore DAT 40 is a LVD SCSI device, so it works best with a LVD SCSI interface. It can be used in a SE SCSI interface if LVD type is not available. It is *not* compatible with HVD SCSI interfaces. The SE mode has stricter cable length limits than LVD: with Ultra SCSI speeds, the total bus length must be 1.5m or less. With both internal and external devices on the same bus, it's all too easy to break this limit.

Connecting conflicting SCSI types together may cause problems: the SCSI bus may not work at all until the "wrong type" device is removed. Some older SE devices may actually be physically damaged if connected to a HVD bus. A HVD device will work only with a HVD SCSI bus.

The terminators must also be the correct type to match the bus: a wrong kind of terminator may cause problems too.

For a quick (and slightly humorous) look on SCSI, see this link:
http://home.comcast.net/~SCSIguy/SCSI_FAQ/SCSIcommandments.html

MK

[chad_c]

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