matt@iquery.UUCP (Matt Reedy) (11/12/89)
Here is the summary of the mail responses and other postings regarding my
cartridge tape questions. Many, many thanks to all who contributed.
matt
---
Matthew Reedy UUCP: cs.utexas.edu!swrinde!dpmizar!iquery!matt
Programmed Intelligence Corp.
400 N Loop 1604 E, Suite 100
San Antonio, TX 78232 (512) 490 6684 Fax: (512) 490-3590
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Date: Thu, 26 Oct 89 18:18:11 EDT
From: doc@lc15a.att.com (David W Mundhenk)
This certainly is a confusing area, isn't it?
I've been trying to decipher this myself, so maybe
we can help each other.
I have a Mountain 60MB Tape Drive on my 386 at home.
It is the same one the AT&T/Olivetti machines use(d),
so I'm pretty sure it will work with AT&T UNIX.
I haven't tested this yet, but will, soon. I have also
heard that this drive can READ tapes from AT&T 3B2
computers, I assume the SCSI ones and not the old
3B2/400 "wheezer" (floppy tape?). I will test this
soon also. I have some sources written out on a
3B2/600 60MB tape I would like to have on my 386...
Regarding the 'QIC' standards, there seem to be a lot
of them ;-). Drives by EVEREX use QIC-02 and QIC-36.
I don't know which the Mountain is, but I'll check.
Anyway, that's all I have now. If you can forward any
other info, or post a summary I would appreciate it!
Thankx,
--
Dave Mundhenk [...!att!lc15a!doc]
EMAIL: ...!att!lc15a!doc | "I can't complain but | /^,
VOICE: (201)-580-4943 | sometimes I still do"| / } _, , , __
#include <std.disclaimer> | - Joe Walsh | /_./ (_l |/ <~_
From: <swrinde!cs.utexas.edu!convergent.com!mitisft!dold>
Date: Thu, 26 Oct 89 18:59:21 -0700
Subject: Re: Cartridge tape questions
matt@iquery.UUCP (Matt Reedy):
Archive makes 4 drives that we use:
QIC-02 interface Full height 5945L-3 60MB
SCSI interface Full height 5945S 60MB
SCSI interface 1/2 height 2060S 60MB
SCSI interface 1/2 height 2150S 125-150MB
The Archive 2150S is the only one that I would recommend for purchase today.
The Archive 2150S Viper drive can read four different formats
from a pre-written tape:
QIC-11 four track 20MB
QIC-24 nine track 60MB
QIC-120 fifteen track 125MB
QIC-150 eighteen track 150MB
It cannot write QIC-11 nor QIC-24.
It will decide on a default write format, which could be overridden,
based on the cartridge it detects, according to the spacing
of the BOT hole set.
DC-300 can't write the default of QIC-24.
DC-600A default is QIC-120, 125MB
DC-600XTD recent name change to DC600-6150
default QIC-150, 150MB.
You can use DC600A with no problem, it just gives 125 instead of 150MB.
DC-600XTD / DC600-6150 are still a little scarce.
Looking at 600 feet of tape, laid out on a table:
BeginningOfTape EndOfTape
| |
________________________________________________________________________
0 0 0 0 0
0 0 0 0 0 0
________________________________________________________________________
->| |<- 18" 18" ->| |<-
->| |<- 18" 18" ->| |<-
->| |<- Media Detect Distance ->| |<-
DC300 - 36"
DC600A - 48"
DC6006150 - ?"
---
Clarence A Dold - dold@tsmiti.Convergent.COM (408) 434-5293
Date: Sat, 28 Oct 89 11:08:08 MST
From: swrinde!cs.utexas.edu!math.arizona.edu!rsm (Robert Maier)
The following comments may prove helpful.
Firstly, it is a bit incorrect to speak of a `SCSI tape drive'. A
SCSI tape drive is simply a tape drive equipped with a SCSI
controller, so that it can be cabled directly to a SCSI bus. The
controller is frequently (though not always) built right into the
drive, so it seems to be an integral part of it.
Also, your question about `byte swapping' is a bit confused. It is
normally the host computer and its operating system that determine the
order of bytes in the data blocks on the tape. It is the tape drive
itself that determines the order of bytes in the block headers, in
accordance with the tape formats that it's designed to understand.
But your request for a `table' is eminently reasonable. There is
indeed a table with columns like
tape size cartridge number number bits per
(megabytes) (DC****) of tracks inch
I have a copy of it in my office, but since I'm not there now I can't
supply it at the moment...
The difficulty in getting older tape drives to read newer tapes is
simply that they have trouble resolving the tape tracks! An older
tape drive finds it hard to find and read the 32 tracks per tape that
the new 150MB cartridges use.
In the Unix world, the tape format (i.e. the format of the headers on
the tape, not the number of tracks or the number of bits per inch) is
more or less standardized. That's why the above table really tells
you everything that you need to know. QIC-24 format is the standard,
although many drives (e.g. those on Sun workstations) will read the
older, very similar QIC-11 format. (QIC-11 format was, I believe, the
original quarter-inch tape format invented by Archive. There are
various other QIC-* formats, but they don't show up much in the Unix
world.)
Appended below is a copy of an article that was posted to Usenet by
John Gilmore about a year ago, that tells a lot more. Note that it
was written before the new 32-track, 150MB cartridges came on the
market; otherwise, it's up to date.
Hope these comments help...
--
Robert S. Maier | Internet: rsm@math.arizona.edu [128.196.128.99]
Dept. of Math. | UUCP: ..{allegra,cmcl2,hao!noao}!arizona!amethyst!rsm
Univ. of Arizona | Bitnet: maier@arizrvax
Tucson, AZ 85721 | FAX: +1 602 621 8322
U.S.A. | Voice: +1 602 621 6893 / +1 602 621 2617
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>Date: Thu, 18 Aug 88 02:56:03 PDT
>From: hoptoad.UUCP!gnu@cgl.ucsf.edu (John Gilmore)
>Subject: Cartridge tape formats and sizes (/dev/rst0 versus /dev/rst8)
There seems to be massive confusion about cartridge tapes. It's really
simple combinations of three different parameters.
There are two variants of the mechanical tape drive -- 4-track and
9-track. The tracks are used like on an 8-track audio tape (run all the
way down the tape on one track, then mechanically slide the head up or
down and do another pass of the tape.) The 9-track version can store
9/4ths as much data as the 4-track version. The 9-track version will read
4-track tapes but the tapes it writes can be marginal for reading on
4-track machines, because the tracks are thinner. Mostly they work.
There are two variants of the tapes themselves. One is 450 feet long
(DC300XL style) and the other is 600 feet long (DC600A style). They use
different magnetic coatings because the tape has to be thinner to fit 600
feet into a cartridge. Some older tape drives can only read/write the 450
foot tapes because their heads can't cope with the new magnetic coatings.
There is a sense hole on the cartridge (up near the write protect tab)
that lets the newer drives figure out how to set up the head for this
particular tape. The actual end-of-tape sensing is done with small holes
punched in the tape itself, detected with an LED, a mirror in the
cartridge, and a photocell, so that works fine for either tape length.
There are two variants of the bit format that controllers record on the
tape. One is called QIC-11, the other is QIC-24. QIC-11 is the original
Archive format (Archive Corp. started the whole 1/4" streaming cartridge
business). When a standards committee got a hold of it, they changed it
(of course) to QIC-24. In both cases, the tape contains 512-byte blocks
of data with small headers on them. For QIC-11, the block number in the
header is 8 bits; for QIC-24, the number is 24 bits. That is essentially
the only difference between the two. It was changed because in unusual
error recovery situations it's possible for the tape to move more than 256
blocks (at 90 inches per second and 8000 bits per inch, things go by
quickly -- think about it) and the controller could lose track of where it
was on the tape. Both formats hold the same amount of data on a given
tape.
If you make up a table of this stuff, you start seeing some familiar
numbers:
Tape 450' 600'
Drive
4-track 20MB [no such drives used in Suns]
9-track 45MB 60MB
The hardware takes care of 4-track/9-track and tape size issues, so all
you have to specify in software is whether you want QIC-11 or QIC-24
formatting. /dev/rst0 is QIC-11 and /dev/rst8 is QIC-24. I linked them
to /dev/rst.qic11 and /dev/rst.qic24 so I could just do it without looking
it up.
I believe Sun should have made the tape driver software attempt to read
tapes in both QIC-11 and QIC-24 format, like reel-to-reel tape drives
which will read whatever density you throw at them. They didn't,
unfortunately, so if you try to read a tape that's in the other format, it
looks like a totally empty tape (you get a "no data" error). Just rewind
and try again with the other format. If you get "no data" in both
formats, you really have a blank tape (or one recorded in yet some other
random format).
There are a few other manufacturers who use QIC-24 tape drives; the IBM
PC/RT is one. Apollos may be another, I'm not sure. Very few of the IBM
PC 1/4" tape drives use QIC-24; they all went off in different directions.
I don't know of any current production machines that use QIC-11 only; it's
obsolete.
Sun used to make all their distribution cartridges in 4-track, QIC-11
format on 450 foot tapes [20MB], since they can be read by all Suns.
Starting with SunOS 4.0, they are now making Sun-4 tapes in QIC-24 on
9-track, 600 ft tapes [60MB] which reduces the number of tapes by a factor
of 3. I am not sure whether Sun-3 tapes have been switched, though I
think all Sun-3's can read 60MB QIC-24 tapes unless they were upgraded
from Sun-2's. However, older boot PROMs can't boot from a QIC-24 tape
(they never ask the tape controller to try QIC-24 mode, and it's too dumb
to do it itself), which is why you may need a boot PROM upgrade from Sun
Tech Support to boot SunOS 4.0 from 1/4" tape.
[I wrote the 'ar' driver for 1/4" tape on Sun-1's -- my first Unix driver,
and it was really bad -- and maintained the boot code for tape drives
through the first Sun-3's.]
John Gilmore
Date: 30 Oct 89 15:30:40 PST (Mon)
From: swrinde!cs.utexas.edu!sactoh0!jak (Jay A. Konigsberg)
I don't know how to fill in the table, but I do know that a 3B2
500/600/700 with a 60/120 MB SCSI drive can read the 60MB SCSI
tapes from an AT&T 6386 running AT&T 386 Unix. Also, if the 3B2
tape was written in 60 MB format it can be read by the 6386.
This is a fairly narrow case, but I believe the connection is the
SCSI interface. This was done at a company I used to work for.
--
-------------------------------------------------------------
Jay @ SAC-UNIX, Sacramento, Ca. UUCP=...pacbell!sactoh0!jak
From: neese@adaptex.UUCP
Date: 28 Oct 89 16:35:00 GMT
QIC refers more to the data format than to the actual interface. With a SCSI
tape drive their is also a QIC standard data format. For instance, I have
a Cipher ST-150S SCSI 1/4" Tape drive that reads/writes data in QIC-120
(DC-600A) and QIC-150 (DC-600XTD, DC-6150) data formats. It will also
read QIC-60 data formats (DC-600A). Whether or not the interface is a SCSI
or a QIC controller, has no bearing on the data format. Hope this helps.
Roy Neese
Adaptec Central Field Applications Engineer
UUCP @ {texbell,attctc}!cpe!adaptex!neese
merch!adaptex!neese
From: witold@cs.washington.edu (Witold Paluszynski)
Date: 29 Oct 89 22:56:13 GMT
Well, there appears to be lots of QIC standards but the answer to
this question is simple: they are generally INCOMPATIBLE. I was
recently shopping for a quarter inch drive with similar objectives
(compatibility with other systems) and I was amazed to discover
that 60 MB drives were incompatible with 150 MB drives. Yes, you
can read a 60 MB tape in a 150 MB drive, but you can't write it.
What I would expect is the sort of upwards compatibility as with
9 track tapes, where even the newest drives can write 800 bpi tapes.
I guess the manufacturers have discovered that with that much
compatibility people just keep using their old drives instead of
replacing them with new ones all the time. So they were careful to
prevent this kind of disaster by designing incompatible standards.
I hope someone can prove me wrong.
Witold
What tends to happen with quarter inch tapes is that to get more data
onto a tape, successive standards define more tracks on the tape.
As the number of tracks on a tape increase, their width decreases
(after all, its still 1/4 inch :-)
When it comes to writing a track, the WIDTH of the write head which
creates the track is (approx) the width of the track.
Higher capacity drives therefore have narrower write heads than the older
drives (QIC24 -> QIC150 -> QIC320 etc....).
This means that it is impossible for a "newer" drive to write "wide tracks"
(which the "older" drives can read).
It IS possible however for a "newer" drive to READ tapes written with
wider tracks since the read head fits "inside" tracks (as written by either
drive).
It is therefore possible to build a drive which reads/writes a new format
but can only read older formats.
It is extreemly difficult (read also: expensive) to try and build a drive
to read and write all formats.
-----------------------------------------------------------------
Kevin Jones. | Hewlett Packard Ltd,
| Computer Peripherals Bristol,
kev%hpcpbla@hplb.hpl.hp.com | Filton Road,
| Stoke Gifford,
Tel: 011 44 272 799910 (ext 22351) | Bristol. BS12 6QZ.
| ENGLAND.
-----------------------------------------------------------------
Liam R. Quin, Unixsys (UK) Ltd.
lee@sq.com (a visitor to Canada, not an employee of "sq")
lee@anduk.co.uk (after Christmas, when I return)
As other people have pointed out, one cannot reliably write a 60M cartridge
with a 150M streamer.
For portability, there is no doubt that the 60M cartridges are the most
useful, as this gives you compatibility with Sun, NCR, CCI, Bull, and many,
many others.
A QIC-24 drive can read and write QIC 11 -- the same problems exist as with
150/60M, but to a much lesser extent and it usually works. You have to tell
Sun users to use /dev/rst8 (QIC 24) as it is not the default at many sites.
150 M tape drives
=================
The Archive Viper is the fastest of the SCSI tape streamers I have looked
at, but it is also the most expensive.
The Cypher SCSI drive is acceptably fast (at least under Xenix and 386/ix),
and a lot cheaper. You need 386/ix 2.0.2, I think, in order to ue the
Cypher drive. This also supports the Wangtek SCSI drive, which is slower
again, but not much so.
The viper streams (i.e., moves continuously), even with tar (block size
of 20 == 20Kbyte).
With the other drives, Xenix/SCSI is generally faster, and ordinary tar
seems better than gnu tar.
Tweaking the SCSI disconect size may affect things.
I was using the Adapttec AHA1540S SCSI host adaptor.
This makes a bigger difference than the choice of tape drive, I think.
I am told that the Wangetek 150M cartridge drive works with the Everex
(non-SCSI) controller, which might be cheaper.
I have not tried this.
On some non-386 Bull systems, I have seen and used ESDI streamers (made by
Cypher), but the drivers are soo pathetically written that the performance
was about a factor of 60 slower than a Sun (!!!!!).
I think they should go quite fast ona 386, although most ESDI controllers
for the PC don't support many devices so this might not be very useful.
Although they can read 60M QIC 24 (not QIC11) tapes, these drives all seem
to have problems with low-density tapes, and they can neither read from
nor write to them.
Sometimes they simply sit there retrying the first block.
60 M tape drives
================
There are problems with these in 25MHz machines, but I have no idea why.
Unixsys [sic] normally uses the Wangtek drive, although they used the Bell
Technologies drive on some earlier machines. No major problems, but if you
let them get too dirty, they may start running off the end of tapes.
Again, xenix is *much* faster, but gnu tar is a big win under 386/ix.
The Cypher 60M drive seems fine, as does the Tandberg. I have also used
an Archive drive, but the extra cost might not be justified.
It is worth using a Wangtek or compatible drive, as both Xenix and Unix
have support for them.
The Wangtek controller is a full-length board with a 25-pin connector at
the back, and if you connect this to a printer you destroy the printer
(or so we were told by a customer!).
But we had no other real problems.
Hope this is of some help. Feel free to mail me for more information.
I only have names of vendors and suppliers in Britain, of course,
although you are welcome to ask me for these.
This posting in no way relates to official Unixsys policy.
I am posting on my own behalf.
Lee
----------------------------------------------------------------
--
Matthew Reedy UUCP: cs.utexas.edu!swrinde!dpmizar!iquery!matt
Programmed Intelligence Corp.
400 N Loop 1604 E, Suite 100
San Antonio, TX 78232 (512) 490 6684 Fax: (512) 490-3590