My original question was:
> I have an ATL P-1000 tape library (with two DLT-7000) drives hanging off of
> a KZTSA (FWD) adapter on an old DEC3000/400 workstation. We use the tape
> library to backup our disks using NSR software.
>
> I'm interested in adding some hard disks to the KZTSA bus. According to the
> KZTSA manual, up to 15 16-bit FWD SCSI devices are supported (subject to
> the operating system). I have a couple of questions:
>
> 1) Does Digital UNIX 4.0D support the full 15 devices on a fast wide
> differential SCSI bus?
> 2) Are there any practical difficulties in daisychaining some additional FWD
> devices to the tape library? The scu utility shows three devices currently
> on the bus: the tape library changer and the two DLT7000 drives. I assume
> that I could add another 12 devices to the bus. Would the library's
> throughput be adversely affected if there were several additional FWD
> hard disks on the bus?
The replies received so far indicate that:
1) Digital UNIX doesn't yet support wide addressing, but will with some future
major release.
2) Adding disks to the same bus is potentially dangerous in the sense that all
of the FWD devices are sharing the 20 MB/sec max bandwidth and I will probably
see a degradation in backup performance if I were to hang a bunch of disks
off the same bus as the tape library.
Based on this, it seems like the solution is to invest in another KZTSA adapter
(discontinued, but still available from some resellers) for the DEC3000/400
and hang the new FWD disks off of that bus.
Thanks to:
Alan Rollow <alan_at_nabeth.cxo.dec.com>
Chris Ruhnke <i769646_at_smrs013.mdc.com>
Tom Blinn <tpb_at_zk3.dec.com>
for their help.
Richard Eckman
NASA Langley Research Center
Hampton, VA
Received on Wed Jul 22 1998 - 01:16:21 NZST