Can 6157-002 tape drive be forced to write in -001 form?

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5 total messages Started by Peter A. Blemel Thu, 02 Nov 1989 10:27

#516

Author: Peter A. Blemel
Date: Thu, 02 Nov 1989 10:27

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   We have a 6157-002 tape drive on a 6150/135 running AIX 2.2.1. I have
been trying to figure out how to make this thing write tapes that a normal
tape drive can read. By normal I mean the -001, Suns, Decstations, etc.

   When we first got the machine, the tape didn't work at all. IBM 
inadvertantly sent a 001 to replace the bad -002. We were quite happy in
our ignorance because we could interchange tapes with the Sun. Recently
that drive died, and we were given a 002 because IBM wanted to rectify
its mistake.

   Now nothing (except the RT itself) can read tapes the RT writes. This
is a considerable problem because we do all our development on this machine
and port away from it. It can read tapes written by these other machines, but
not write tapes that they can read. Is there anything, short of buying a
001, that I can do?

   This drive is also rediculously slow. I have the buffer size maxed out
(tar at 800), and it still takes forever to write even 10k. Is there
any way to switch this data compression or whatever it is off, or am I
missing some parameter to make it go faster?

   Any pointers would be greatly appriciated.

Thanks
Peter
-----
peter@hydrovax.nmt.edu
peter@amber.nmt.edu
(505) 835 4761
(505) 255 8611

Re: Can 6157-002 tape drive be forced t

#520

Author: silver
Date: Thu, 02 Nov 1989 23:32

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Re: 6157-002 tape drives being slow

Yes, I agree they aren't speed-demons, but I have obtained a tremendous
speedup with buffering.  The daily backups we make (5-8Meg) take
only 4-5 minutes.  The fulldumps (200+Meg) take only 75-80 minutes.
That's not including the time to switch between the 4 tapes it requires.

All we changed in the cpio (daily) or backup (fulldump) calls was to
include -C2000 for a block/buffer size of 1 Meg.  We have 12 Meg. of
real memory, so page-faulting is not much of a problem.

As far as reading -001 tapes on a -002, I'd like to answer to that
if anyone ever discovers one.

All of this is from a RT/125 with 3x310 Meg disks (mostly empty).

Edward A. Silverstein
silver@director.beckman.uiuc.edu

Re: Can 6157-002 tape drive be forced t

#524

Author: David L. Luner
Date: Fri, 03 Nov 1989 23:12

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In article <213600004@s.cs.uiuc.edu> silver@s.cs.uiuc.edu writes:
>
>Re: 6157-002 tape drives being slow
>
>As far as reading -001 tapes on a -002, I'd like to answer to that
>if anyone ever discovers one.

If I recall correctly, and I'll check tonight, a -002 *can* read tapes 
written by a -001, but not the other way around. (And there is no way
to make a -002 write tapes in such a way that a -001 can read them).

	-- David

Re: Can 6157-002 tape drive be forced t

#537

Author: Daniel Ehrlich
Date: Thu, 09 Nov 1989 21:13

33 lines
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In article <213600004@s.cs.uiuc.edu> silver@s.cs.uiuc.edu writes:

silver> Nf-ID: #R:nmtsun.nmt.edu:3425:s.cs.uiuc.edu:213600004:000:731
silver> Nf-From: s.cs.uiuc.edu!silver    Nov  2 17:32:00 1989
silver>
silver> Re: 6157-002 tape drives being slow
silver>
silver> Yes, I agree they aren't speed-demons, but I have obtained a tremendous
silver> speedup with buffering.  The daily backups we make (5-8Meg) take
silver> only 4-5 minutes.  The fulldumps (200+Meg) take only 75-80 minutes.
silver> That's not including the time to switch between the 4 tapes it requires.
silver>
silver> All we changed in the cpio (daily) or backup (fulldump) calls was to
silver> include -C2000 for a block/buffer size of 1 Meg.  We have 12 Meg. of
silver> real memory, so page-faulting is not much of a problem.
silver>
silver> As far as reading -001 tapes on a -002, I'd like to answer to that
silver> if anyone ever discovers one.

One could always read -001 tapes on a -002 drive.  I think the original
question was about `writing' -001 tapes on the -002.  Unfortunately the
answer would appear to be no.  This is on AOS where I have looked at the
sources for the device driver.  There is not even a hint ob being able to do
this.

silver> All of this is from a RT/125 with 3x310 Meg disks (mostly empty).
silver>
silver> Edward A. Silverstein
silver> silver@director.beckman.uiuc.edu
--
Dan Ehrlich <ehrlich@cs.psu.edu>
"A message is not a message until the rules for interpreting it
 are in the hands of the receiver." --Apollo Belvedere Smith

Re: Can 6157-002 tape drive be forced t

#552

Author: Darren Holloway
Date: Thu, 09 Nov 1989 22:47

25 lines
1495 bytes

In article <213600004@s.cs.uiuc.edu>, silver@s.cs.uiuc.edu writes:
> 
> Re: 6157-002 tape drives being slow
> 
> Yes, I agree they aren't speed-demons, but I have obtained a tremendous
> speedup with buffering.  The daily backups we make (5-8Meg) take
> only 4-5 minutes.  The fulldumps (200+Meg) take only 75-80 minutes.
> That's not including the time to switch between the 4 tapes it requires.

You can get about 10-20% more speed than -C2000 by using "dd", as such:

 To do a backup:
  li -Ra /u | backup -ivr -f - -C30 | dd of=/dev/rmt0 bs=30b

 To do a restore:
  dd if=/dev/rmt0 bs=30b | restore -xv -f - -C30

However, I have heard that it is possible to lose your end-of-tape markers
while doing this...You will have to try it yourself and decide.

-- 
-----------------------------------------------------------------------------
Darren G. Holloway	Systems Administrator	       GENIE Computer Systems
UUCP: calgary!xenlink!blender!genieho!{darren|root} REALTIME: +1 403 295 0418
"You'll get there Someday" - Slogan in Hyundai TV Commercial

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