eli@chipcom.chipcom.com (06/23/89)
what is the difference between /dev/rst0 and /dev/rst8 and likewise between /dev/nrst0 and /dev/nrst8 there are some very 'raw' aspects to getting 3/80s running if you don't have a tape drive that you can connect directly to them! i'm currently trying to copy some crucial stuff from the 4.0.3 boot tape so i can boot our new 3/80 machines over ethernet. this installation is turning out to be a bear because we have neither a 3/80 tape drive nor the special cable which can connect an 3/80 to a 3 row scsi connector. i have managed to load the Sys stuff and build a kernel, but i can't download the *^!@#&^* boot loader from the Kvm partition. at one point, i was able to get tar to display the contents of the Kvm tarfile. but i can't read the files! aaaaaaagh. -- eli@spdcc.com, eli@chipcom.com [mail to chipcom.chipcom.com bounces!] -- voice mail: 617 859 1389 -- work phone: 617 890 6844
meo@gatech.edu (Miles O'Neal) (07/05/89)
In article <4107@kalliope.rice.edu> eli@chipcom.chipcom.com writes: | X-Sun-Spots-Digest: Volume 8, Issue 49, message 1 of 11 | | what is the difference between /dev/rst0 and /dev/rst8 | and likewise between /dev/nrst0 and /dev/nrst8 The difference is the tape format. I don't remember the exact definitions, but basically, the 0 devices are for 45MB tape formats, and the 8 devices use the 60MB formats. They aren't interchangeable. Miles
jms@tymix.tymnet.com (Joe Smith) (08/01/89)
In article <114@brazos.Rice.edu> stiatl!meo@gatech.edu (Miles O'Neal) writes: >X-Sun-Spots-Digest: Volume 8, Issue 70, message 1 of 15 > >In article <4107@kalliope.rice.edu> eli@chipcom.chipcom.com writes: >| X-Sun-Spots-Digest: Volume 8, Issue 49, message 1 of 11 >| >| what is the difference between /dev/rst0 and /dev/rst8 >| and likewise between /dev/nrst0 and /dev/nrst8 > >The difference is the tape format. I don't remember the exact definitions, >but basically, the 0 devices are for 45MB tape formats, and the 8 devices >use the 60MB formats. They aren't interchangeable. > >Miles I, too, would like to know the difference between rst0 and rst8 on 1/4 inch tape. The only references I have found are on page 84 of the "Network and System Administration" manual, part 800-1733-10, Rev A, May 1988. rst0 = QIC-11, 9 tracks, 45 Mbytes on 450 ft, 60 Mbytes on 600 ft tape rst8 = QIC-24, 9 tracks, 45 Mbytes on 450 ft, 60 Mbytes on 600 ft tape This implies that the amount of storage depends only on the length of tape and not whether you specify /dev/rst0 vs /dev/rst8. I have been told that the tape drive always stores 512 bytes per tape block. There is a flag bit to say whether more data follows, a count of valid bytes, and a checksum for the block. Is it true that QIC-11 and QIC-24 store the same amount of data on the tape, and just have different standards for encoding the length and checksum? Which format is recommended for doing dumps? Which format should be used for interchanging data with other systems? In other words: when should I use rst0 and when should I use rst8? Joe Smith (408)922-6220 | SMTP: JMS@F74.TYMNET.COM or jms@tymix.tymnet.com McDonnell Douglas FSCO | UUCP: ...!{ames,pyramid}!oliveb!tymix!tardis!jms PO Box 49019, MS-D21 | PDP-10 support: My car's license plate is "POPJ P," San Jose, CA 95161-9019 | narrator.device: "I didn't say that, my Amiga did!"
jipping@cs.hope.edu (Mike Jipping) (08/22/89)
> I, too, would like to know the difference between rst0 and rst8 on 1/4 > inch tape. The only references I have found are on page 84 of the > "Network and System Administration" manual, part 800-1733-10, Rev A, May > 1988. 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
ajy@uunet.uu.net (andrew yeomans) (08/22/89)
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.
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-------------------------- 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
14th June 1989