Pat_Barron@TRANSARC.COM (06/03/90)
A couple of weeks ago, I posted a request for information on QIC tape formats,
and what's compatible with what. A number of people set me mail asking for
a summary of the answers I got. This message that I recieved contains just
about all the information that anyone sent me - since most people sent me
these summaries of what was posted the last few times this was asked. Maybe
it's time for a comp.periphs "Most Commonly Asked Questions" monthly posting...
Many thanks to all who responded!
--Pat.
---------- Forwarded message begins here ----------
Return-path: <analytics!rcsmith@uunet.UU.NET>
X-Andrew-Authenticated-as: 0;transarc.com;Network-Mail
Received: from transarc.com via trymail
ID </afs/transarc.com/usr/pat/Mailbox/8aMdn9b0Bi81E4F05i>;
Tue, 29 May 1990 12:01:13 -0400 (EDT)
Received: from uunet.uu.net by transarc.com (5.54/3.15) id <AA01088> for Pat_Barron; Tue, 29 May 90 12:00:56 EDT
Received: from analytics.UUCP by uunet.uu.net (5.61/1.14) with UUCP
id AA06971; Tue, 29 May 90 12:00:46 -0400
Received: by anagld.analytics.com (5.52/smail2.5/10-10-89)
id AA03681; Tue, 29 May 90 11:31:34 EDT
From: rcsmith@anagld.analytics.com (Ray Smith)
Message-Id: <9005291531.AA03681@anagld.analytics.com>
Subject: QIC tape info
To: Pat_Barron@TRANSARC.COM
Date: Tue, 29 May 90 11:31:30 EDT
Reply-To: rcsmith%anagld@uunet.UU.NET
Return-Receipt-To: rcsmith%anagld@uunet.UU.NET
X-Mailer: ELM [version 2.3test PL40]
Pat,
Here are two summaries of information regarding QIC tape drives.
I hope they are helpful.
-Ray
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Begin summary 1
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
From: Daryl Crandall <uunet!dash.mitre.org!daryl>
Subject: Another summary of 1/4" tape systems
Date: Mon, 30 Apr 90 10:35:30 EDT
A while back I posted a request for a tutorial about cartridge tapes and then
summarized the replies. I continued to get more replies on this subject and
have compiled them into this summary. I'll repeat the original summary and
then append the new summary.
Daryl Crandall
The MITRE Corporation
(703) 883-7278
daryl@mitre.org
###########################################################################
###########################################################################
ORIGINAL SUMMARY
# Date: Mon, 9 Apr 90 11:16:31 EDT
# From: Daryl Crandall <daryl@dash.mitre.org>
# Message-Id: <9004093440.AA07838@dash.mitre.org>
# To: sun-managers@dash.mitre.org
# Subject: 1/4 inch tape summary
# Status: R
###########################################################################
Here is the summary to my posting about a tutorial on 1/4 inch tape drive
systems. I'll repeat the original question.
###########################################################################
Can somebody give me a quick lesson on the types of 1/4 inch cartridge
tape drives and cartridges. I've become terminally confused about
tape lengths, tape capacities, drive write densities, drive read densities,
automatic density switching, compatabilities, number of tracks, QIC-II,
QIC-24, QIC?? ... AAAARRRRGGGHHH!
Why can't tar add to the end of a file written on a 1/4 inch tape?
Why do you have to re-tension?
What is the past, present, and future of 1/4 inch tape drives?
Why is there air? :-)
Daryl Crandall
The MITRE Corporation
7525 Colshire Drive
McLean, Virginia 22102
USA
daryl@mitre.org
(703) 883-7278
###########################################################################
Judging by the number of requests for the summary, There are apparently a
lot of people who are confused on this subject.
There are still several points that need to be cleared up, but I can not spend
much more time on this subject.
First of all there is a Sun document called:
"Sun Tutorial on 1/4 Inch Tape Drives" (Sun Part No: 800-1315-05)
This describes the physical tape mechanism. It does not describe the
industry's evolution of different tape lengths and drive types.
I won't go into the details in this document. Get it, it's worth it!
Other sources of documentation:
> Table 7-7 on page 84 of the System & Network Admin manual, shows
> the relation between some tape aspects.
> The manual pages for ST(4S) provide somewhat heavier type of info.
According to what I have gleaned in the last couple of days, cartridge tape
drives have either 4 or 9 tracks. I haven't gotten any information on
which types of drives have 4 and which have 9 tracks but according to
the Sun tutorial (above) "Tapes written on the 4-track drives can be read
reliably by the 9-track drive" (re-tension if you get errors). According to
the same source, tapes written on 9-track drives may (or may not) be readable
on a 4-track drive.
Tape re-tensioning is necessary relatively frequently to assure that the
tape moves smoothly across the heads and doesn't "chatter" or jerk causing
errors.
Data is recorded on the tape in serpentine tracks. i.e. starting from the
beginning of tape, track 1 is recorded forward until the physical end of
tape is reached and the recording direction is switched to record track 2
in reverse. This process continues until all available tracks have been used.
The erase head is the full width of the tape and is ONLY active during the
1st forward pass erasing ALL TRACKS on the tape.
> What is the past, present, and future of 1/4 inch tape drives?
>
> past: QIC-11, QIC-24, 300' tape, 450' tape
> present: QIC-150, 600' tape
> future: QIC-525, 1000' tape
> They're dead meat - but just like 2400' reels are still with us, 1/4
> inch cartridges will take awhile to decay away, reincarnating in new
> and seemingly wondrous forms at times.
Here is an incomplete table of densities and lengths:
QIC-11 QIC-24 QIC-150
300' 32M ?? ??
450' 45M ?? ??
600' 65M 150M ??
Still need clarification on device assignments (/dev/st0, /dev/st8) and
recording densities (QIC-11, QIC-24, QIC??)
> QIC-11 and QIC-24 are just different formats for writing on the tape.
> QIC-24 is newer, higher density, and has more secure head positioning
> - less susceptibility to misaligned heads screwing things up.
> QIC-11 and QIQ-24 write at the same density but with different
> error correction schemes. One is typically rst0 and the other rst8.
> The write heads don't generate fields strong enough to really
> overwrite existing data; they can only write on blank tracks.
> Why can't tar add to the end of a file written on a 1/4 inch tape?
> You can add to a cartridge tape on which you have a tar record.
> You just first use mt -f /dev/nrst8 fsf 1 (or nrst0 or whatever)
> to skip the first record. The `n' refers to the non-rewinding device.
> Use of /dev/rst8 would result in the tape rewinding after the skip.
Editor's note: I haven't tried this but I had a couple of responses indicating
that it would work. Feedback anyone?
Why is there air?
"We used it to make vacuum column tape drives work. Some of it got
out of the labratory by mistake."
"To fill my bicycle's tires."
"To blow up basketballs."
###########################################################################
Thanks to:
dan@breeze.bellcore.com (Daniel Strick)
ebersman@uunet.uu.net (Paul Ebersman)
chuckles@sne42e.orl.mmc.com (chuck strickland)
Len Evens <sysadm@gauss.math.nwu.edu>
martin@molndal.ericsson.se
stefan mochnacki <stefan@centaur.astro.utoronto.ca>
bit!markm (Mark Morrissey)
yamada-sun!root@nosun.West.Sun.COM (Super User)
jaf@cana.Inference.Com (Jose Fernandez)
###########################################################################
###########################################################################
NEW SUMMARY:
I don't think you will find a 4 track cartrdige tape drive in
any Sun but an obsolete Sun2. (We happen to have one!) Of course, if
you have written 9 tracks on a tape, you won't be able to read 9 tracks
with a 4 track drive.
###########################################################################
One more thing. A 60 Meg tape on a 60 Meg drive will max out at ~47 Meg.`
Try: dd if=/dev/rroot of=/dev/TAPE bs=1k
and wait for the stats when it runs out.
47 Meg is what I got.
###########################################################################
----- Begin Included Message -----
> Why can't tar add to the end of a file written on a 1/4 inch tape?
> You can add to a cartridge tape on which you have a tar record.
> You just first use mt -f /dev/nrst8 fsf 1 (or nrst0 or whatever)
> to skip the first record. The `n' refers to the non-rewinding device.
> Use of /dev/rst8 would result in the tape rewinding after the skip.
Editor's note: I haven't tried this but I had a couple of responses indicating
that it would work. Feedback anyone?
----- End Included Message -----
As far as I have experienced this is working ok. Just use mt -f fsf
and skip as many records as you want. However there is one problem
coming up occationally. There was a bug in the st driver in Sun OS 4.0.0
and the bug is still there in the patched st driver for SPARCstation1.
The problem is that when you add a record on a new tape, a second EOF mark
is written after this one to indicate that this is the end of tape. When
another record is written to the tape the second EOF mark is supposed to be
overwritten. This is not always so. When you try to read the records,
you always get the first one, but to get the second you have to try two times
to skip the second EOF mark or you must multiply your fsf parameter with two
:-).
###########################################################################
Well, I considered responding to the original question, but thought that you'd
probably get better info from someone else. Seems you didn't... also, I have
now found a copy of the *good* info I had read awhile back on this subject.
I include it below, after a couple of comments to your summary. I'd make one
comment to the info I saved though, and that is that at least under 4.0 the
driver *can* detect QIC-11 vs QIC-24 when reading, i.e. it doesn't matter
whether you use rst0 or rst8 *when reading* (this is in fact documented in
st(4S)).
> Here is an incomplete table of densities and lengths:
>
> QIC-11 QIC-24 QIC-150
>
> 300' 32M ?? ??
>
> 450' 45M ?? ??
>
> 600' 65M 150M ??
I do believe that the capacity difference here (as well as the comment about
different densities you quote) is incorrect, i.e. the difference isn't due to
QIC-11 vs QIC-24 but to 4-track vs 9-track. Since Sun more or less switched
from 4-track,QIC-11 to 9-track,QIC-24, this confusion (which seems to be quite
widespread) is understandable.
> Still need clarification on device assignments (/dev/st0, /dev/st8) and
This is well documented in ST(4S) of 4.0, I think.
Hope this helps...
###########################################################################
About a year ago, John Gilmore submitted to Sun-Spots a well-written
description of cartridge tape formats. I've included it below. Save it
and spread it around.
Mike Jipping Internet: jipping@cs.hope.edu
Hope College BITNET: JIPPING@HOPE
Department of Computer Science Voice: Hey!
=========================================================================
>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
###########################################################################
I prepared the following fact sheet on both the 9-track tape unit which we
use, and the Sun cartridges.
The info on the 9-track tape drive was obtained from mtio(4), xt(4S) and a
fair bit of experimentation. If you are lucky, it may also be true for
your own mag tape drives.
The info on the cartridge tapes comes from mtio(4), st(S) and several
contributors to Sun-Spots [sorry, I've forgotten who sent what]. The
bottom line is that there is very little to choose between rst0 and rst8
for the amount of data you get on the tape. However, whichever you choose,
you won't be able to read the tape back on some other machines! Sun-Spots
also explained the problems of booting SunOS installation tapes - If I
remember correctly, the boot proms in the earlier Sun 3 workstations could
only read QIC-11 format. Sun in their wisdom supplied SunOS 4 in QIC-24
format, necessitating users to upgrade their boot proms.
___ ___ ___
Andrew Yeomans PSTN: 0442 230000 ext 3371 |XXX| |XXX| | |
Crosfield Electronics Ltd INTL: +44 442 230000 |XXX| |XXX| |___|
Three Cherry Trees Lane Fax: 0442 232301 ___ ___ ___
Hemel Hempstead UUCP: ajy@cel.uucp |XXX| | | | |
Hertfordshire or mcvax!cel!ajy@uunet.uu.net |XXX| |___| |___|
HP2 7RH ___ ___ ___
England .. all opinions are my own, etc. |XXX| |XXX| | |
'The network is the bottleneck' |XXX| |XXX| |___|
-------------------------- cut here -------------------------------------
Magnetic tape devices
---------------------
xt - Xylogics 472 1/2 inch tape controller
------------------------------------------
Device name Maj Min Rewind on close Density Block size
Fixed block size mode:
/dev/mt0 8 0 Rewinding 1600 bpi 2048 bytes
/dev/nmt0 =/dev/mt4 8 4 Non-rewinding 1600 bpi 2048 bytes
/dev/mt8 8 8 Rewinding 6250 bpi 2048 bytes
/dev/nmt8 =/dev/mt12 8 12 Non-rewinding 6250 bpi 2048 bytes
Variable block size (raw) mode:
/dev/rmt0 30 0 Rewinding 1600 bpi Variable
/dev/nrmt0 =/dev/rmt4 30 4 Non-rewinding 1600 bpi Variable
/dev/rmt8 30 8 Rewinding 6250 bpi Variable
/dev/nrmt8 =/dev/rmt12 30 12 Non-rewinding 6250 bpi Variable
For compatibility reasons, the non-rewinding devices can be accessed by
either of the two names given.
'tar' and 'dump' default to using /dev/rmt8 (rewinding).
'mt' defaults to using /dev/rmt12 (non-rewinding).
The tape density may only be changed when writing if the tape is at the
load point, and if the drive is set to 'host-selectable density'.
The actual recorded tape density is used when reading or when writing
other than at load point, and any attempts to set it (on the front panel
or by device name) are ignored. The density status lights show the
selected density, not the actual recorded tape density.
st - SCSI 1/4 inch cartridge tape
---------------------------------
Device name Maj Min Rewind on close Format Block size
/dev/rst0 18 0 Rewinding QIC-11 512*n bytes
/dev/nrst0 18 4 Non-rewinding QIC-11 512*n bytes
/dev/rst8 18 8 Rewinding QIC-24 512*n bytes
/dev/nrst8 18 12 Non-rewinding QIC-24 512*n bytes
There are two parameters to consider with 1/4 inch cartridge tapes.
One is the number of tracks (4 or 9), the other is the encoding format
(QIC-11 or QIC-24). QIC-11 uses 1 byte block numbers, while QIC-24 uses
3 byte block numbers. QIC-11 has fractionally greater tape density,
while QIC-24 is more robust.
Tapes written by a 4-track drive can be read on a 9-track drive.
Tapes written by a 9-track drive may sometimes be read on a 4-track
drive, but with no guarantee of success.
Old Sun-2 machines can only write 4-track QIC-11 tapes.
Newer Sun-2 machines can only write 9-track QIC-11 tapes.
Sun-3 machines can only write 9-track QIC-11 or 9-track QIC-24 tapes.
Andrew J. V. Yeomans
###########################################################################
We record something like 55 Meg on 600 ft tapes regularly.
The last person who claimed to have results like yours with dd discovered he
had inadvertently slipped a shorter tape in. However, I do admit that
wouldn't explain 47 Meg.
###########################################################################
I don't know if this is a repeat msg but:
The important difference in capacities seems to be related to the overhead
associated with small blocking factors.
Try it with bs=126 (= 63k) and things should improve.
I think the question was referring to the 'r' option of tar, which,
according to the man page, will "write the named files on the end of the
tarfile. Note: this option *does not work* with quarter-inch archive tapes."
Not that i've ever had any need to use this option. I'd just be curious to
know if any of the answers you got addressed this.
Just to further your confusion about tape drives (:->), I'll tell you
this interesting tidbit. A while ago one of the engineers here was
looking at two boxes of tape cartridges (we buy 3M carts, and they
come 5 to a box). One box had DC-600As in it, the other had DC-6150s.
As you probably know, the 600As are 60-megabyte types, and the 6150s
are 150 megabytes. Anyhow, he noticed that each box had a `Technical
Brief' written on the side; _both_ boxes briefs had this information:
CHARACTERISTICS
620 ft (189.0m)
12500 ftpi
550 oersted tape
ftpi stands for Flux Transitions Per Inch.
If you beleive those numbers, it looks like 6150s and 600As are
*exactly the same* tape! Now, I said to this engineer, "Surely 3M
wouldn't sell the same tape under two model numbers!" So, I stuck a
DC-600 in the drive, and gave my usual backup command to the computer
-- the same command that I use with the 6150s (if you're interested,
the command was `dump 5cfsu /dev/rst0 1500 /home'). The dump went
without a hitch; I then did a `restore t' to see if I could read the
tape, and of course, all the files were present. I didn't actually go
so far as to extract the contents of the files, but having been able
to extract the names makes me wonder if there is any difference at all
between the 600A and the 6150.
###########################################################################
More thanks to:
Len Evens <sysadm@gauss.math.nwu.edu>
stevej@Synopsys.COM (Steven Jukoff)
Sven Ole Skrivervik <svenole@vest.sdata.no>
per@erix.ericsson.se (Per Hedeland)
cel!ajy@uunet.uu.net (andrew yeomans)
sysadm@gauss.math.nwu.edu Tue Apr 10 11:46:28 1990
stevej@Synopsys.COM (Steven Jukoff)
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
End summary 1
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Begin summary 2
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
From: matt@iquery.UUCP (Matt Reedy)
Subject: SUMMARY: cartridge tape standards
Keywords: QIC cartridge tape standards
Message-ID: <171@iquery.UUCP>
Date: 11 Nov 89 21:15:23 GMT
Organization: Programmed Intelligence, San Antonio
Lines: 412
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
----------------------------------------------------------------------
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
----------------------------------------------------------------------
>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
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
End summary 2
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Ray Smith | UUCP: {uunet,aplcen,sundc}!anagld!rcsmith
Analytics, Inc. | ARPA: rcsmith@analytics.com or
Suite 200 | anagld!rcsmith@uunet.uu.net or
9891 Broken Land Parkway | RCSmith@DOCKMASTER.NCSC.MIL
Columbia, MD 21046 | Voice: (301) 381-4300 Fax: (301) 381-5173
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=