15 May
2007
15 May
'07
3:44 a.m.
From: Jim Leonard <trixter at oldskool.org>
I have several 35/70GB DLT drives on various systems and they all do between
240MB/minute to 400MB/minute depending on the speed of the disk systems (and
to some extent CPU's) they are backing up so yours certainly seems in the
ball park. You can't go by interface (10MB/s) or bus (132MB/S) speed, it's
purely down to the highest rate the drive can stream at and making sure you
can feed it data fast enough to keep it in 'streaming' mode.
Jim
Don't confuse interface speed vs. actual
media speed.
True, but I didn't have a basis for comparison. I'm hearing that 4MB/s
is indeed slightly above par, so I guess I should be happy . 
15 May
15 May
2:07 p.m.
Jim Attfield wrote:
On the system I had it hooked up to (a 933MHz Linux box with hardware
RAID) keeping the drives fed was no problem.
Anyway, I'm happy to see that, although seeming to need a cleaning tape
every 4 loads or so, they function as expected :-)
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Help our electronic games project: http://www.mobygames.com/
Or check out some trippy MindCandy at http://www.mindcandydvd.com/
A child borne of the home computer wars: http://trixter.wordpress.com/
From: Jim
Leonard <trixter at oldskool.org>
I have several 35/70GB DLT drives on various systems and they all do between
240MB/minute to 400MB/minute depending on the speed of the disk systems (and
to some extent CPU's) they are backing up so yours certainly seems in the
ball park. You can't go by interface (10MB/s) or bus (132MB/S) speed, it's
purely down to the highest rate the drive can stream at and making sure you
can feed it data fast enough to keep it in 'streaming' mode. Don't confuse interface speed vs. actual
media speed.
True, but I didn't have a basis for comparison. I'm hearing
that 4MB/s
is indeed slightly above par, so I guess I should be happy . 
2:27 p.m.
On Tuesday 15 May 2007 14:07, Jim Leonard wrote:
Anyway, I'm happy to see that, although seeming to
need a cleaning
tape every 4 loads or so, they function as expected :-)
Hmm, that's not good. You probably either have a drive head that's
going bad, or your tapes are starting to shed oxide. (Maybe just some
tapes in particular - can you correlate when the "use cleaning tape"
light goes on with any particular tape you're using?)
DLT drives should last at least hundred of tape mounts before you need
to clean them, assuming the tapes and drives are OK.
Pat
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
3:53 p.m.
--- Patrick Finnegan <pat at computer-refuge.org> wrote:
On Tuesday 15 May 2007 14:07, Jim Leonard wrote:
I replaced a drive here at work that did just the same
thing - it requested a cleaning tape very frequently.
This was a DLT7000. I swapped out the drive and hooked
it up to my PC to troubleshoot it. I found that while
it gave no errors when writing tape, it could not read
back what it had just written! I tried several times
with known good tapes - but tar could not make sense
of what it had written. So watch out there...
Also, I have found that the drive will basically ask
for a cleaning tape any time it gets confused by what
it's reading off a cartridge (for example, when
putting a tape written in a 7000 into a 4000). But
once you start to write data to the tape, and remount
it, the problem doesn't come back. (Shutting off the
drive and turning it back on will clear the "cleaning
tape" light)
-Ian
Anyway, I'm happy to see that, although
seeming to
need a cleaning
tape every 4 loads or so, they function as
expected :-)
Hmm, that's not good. You probably either have a
drive head that's
going bad, or your tapes are starting to shed oxide.
(Maybe just some
tapes in particular - can you correlate when the
"use cleaning tape"
light goes on with any particular tape you're
using?)
DLT drives should last at least hundred of tape
mounts before you need
to clean them, assuming the tapes and drives are OK.
7:06 p.m.
Mr Ian Primus wrote:
Also, I have found that the drive will basically ask
for a cleaning tape any time it gets confused by what
it's reading off a cartridge (for example, when
putting a tape written in a 7000 into a 4000). But
once you start to write data to the tape, and remount
it, the problem doesn't come back. (Shutting off the
drive and turning it back on will clear the "cleaning
tape" light)
That sounds very much like what I'm going through, since I also had a
dozen DLTIV tapes that came with the drive, all of unknown origin.
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Help our electronic games project: http://www.mobygames.com/
Or check out some trippy MindCandy at http://www.mindcandydvd.com/
A child borne of the home computer wars: http://trixter.wordpress.com/
17 May
17 May
3:58 a.m.
On Tue, 15 May 2007 12:53:49 -0700 (PDT)
Mr Ian Primus <ian_primus at yahoo.com> wrote:
I replaced a drive here at work that did just the
same
thing - it requested a cleaning tape very frequently.
Once I had that problem too.
I did some tests and finaly came to the
conclusion that the PSU in the external SCSI box was too weak for the
DLT. It seems DLTs like to suck big peek currents. The PSU could not
cope with this, voltage got instable and confused the DLT.
--
tsch??,
Jochen
Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/
7:15 a.m.
On Thu, 17 May 2007, Jochen Kunz wrote:
On Tue, 15 May 2007 12:53:49 -0700 (PDT)
Mr Ian Primus <ian_primus at yahoo.com> wrote:
Another thing to check: I've seen a couple of DLT7000 drives where the
Molex power connector pins were slightly undersized, making poor contact
with the supply cable. This can cause exactly the same symptoms. I ended
up pinching the female pins on the cable with a small screwdriver to
create a tighter fit. Solved the problem in my case.
And, yes, current requirements for these drives are generally too high for
external SCSI cases intended for hard disks or CD-ROMs. I cannabilized
a mini ITX power supply to provide a heftier source in the last case I
assembled.
Also worth updating the firmware. All of mine were either HP or Compaq
OEM units and both vendors offer Windows and Linux based diagnostic
programs (with firmware uploader) available. At one point, I was able to
find the "official" Quantum version, but it seems to have vanished from
their web site.
Steve
--
I replaced a drive here at work that did just the
same
thing - it requested a cleaning tape very frequently.
Once I had that problem too.
I did some tests and finaly came to the
conclusion that the PSU in the external SCSI box was too weak for the
DLT. It seems DLTs like to suck big peek currents. The PSU could not
cope with this, voltage got instable and confused the DLT. 
15 May
15 May
3:34 p.m.
At 1:07 PM -0500 5/15/07, Jim Leonard wrote:
Anyway, I'm happy to see that, although seeming to
need a cleaning
tape every 4 loads or so, they function as expected :-)
That's not normal, are you in a very dirty environment, or using
tapes that are in bad condition?
I've been told by one of their FE's that leaving a tape unloaded in
the drive might be a good idea to help keep dirt out of an external
drive.
Zane
--
| Zane H. Healy | UNIX Systems Administrator |
| healyzh at aracnet.com (primary) | OpenVMS Enthusiast |
| MONK::HEALYZH (DECnet) | Classic Computer Collector |
+----------------------------------+----------------------------+
| Empire of the Petal Throne and Traveller Role Playing, |
| PDP-10 Emulation and Zane's Computer Museum. |
| http://www.aracnet.com/~healyzh/ |
7:07 p.m.
Zane H. Healy wrote:
At 1:07 PM -0500 5/15/07, Jim Leonard wrote:
The tapes are definitely not new, so that may be it.
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Help our electronic games project: http://www.mobygames.com/
Or check out some trippy MindCandy at http://www.mindcandydvd.com/
A child borne of the home computer wars: http://trixter.wordpress.com/
Anyway, I'm happy to see that, although
seeming to need a cleaning
tape every 4 loads or so, they function as expected :-)
That's not normal, are you in a very dirty environment, or using tapes
that are in bad condition?
6271
days inactive
6273
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8 comments
7 participants
participants (7)
-
healyzh＠aracnet.com -
ian_primus＠yahoo.com -
james＠attfield.co.uk -
jkunz＠unixag-kl.fh-kl.de -
pat＠computer-refuge.org -
snhirsch＠gmail.com -
trixter＠oldskool.org