[Info-vax] Modern VMS (e.g. V8.4) tape installation?

[Michael Kraemer]

Ken Fairfield schrieb:

> We had a pair of 8mm drives connected to HSC50's.  Pardon
> me, but I don't recall the 3rd party vendor who made those
> after two decades have passed...  I do recall very clearly
> that we were regularly swapping out one or the other of the
> drives.  They'd fail about once/month, IIRC.  (Don't ask
> me the failure mode, sorry, I don't remember.)

Sounds familiar.
Internal 8mm drives in 8xxx VAXen were a real pita.
Whether this was caused by crappy drives,
the driver software or VMS itself, I don't know.
OEM 8mm drives hooked up to Unix workstations
(including those from DEC) used to work much better.
You always needed a lot of patience though.

> We also attempted to use one of these drives as for data
> logging in our data acquisition system.  I wish I remembered
> the details, I don't, but it seems we may have had a 3rd
> party SCSI adapter or similar in our VAX 11/785.  Problem
> was the drive would go into an "allocated to another user"
> state regularly and couldn't be recovered without a system
> reboot.  Yes, that can happen with any tape drive, but it
> happened *frequently* with the 8mm, enough that we couldn't
> use it.  Oh, and it never happened with the 6250 bpi drives.

Well, to be fair, you should also mention how many data an 8mm
can hold as compared to those half inch tapes,
not to mention the price of the drives.
If your data are/were mostly sequential in nature
(data logging!),
8mm was hard to beat in price, performance and form factor.
The 5GB drives could stream with 500kB/s iirc,
that wasn't exactly shabby at that time.
It also meant some three or four hours of data taking
until the next tape change. Try that with a half inch,
and you'd have to change tape every few minutes and
end up with pile of bulky tape media.