QIC-11, QIC-24 and dump(8) tape length

QIC-11, QIC-24 and dump(8) tape length

Post by Johan Wid » Thu, 02 Aug 1990 19:55:00

What are the good and bad points of the QIC-11 and QIC-24 tape formats?
We have a Sun which supports both formats and I would like to know if one
of these formats is better in some sense.

I would also like to know how to calculate dump(8) tape length for a say
9 track cartidge tape. I do not have the source for Sun dump but I suspect
that dump regards all tapes as 8 track (8 data plus parity). My guess is also
that 9 track cartridge tape is used by writing 8 data bits and 1 parity bit.
Is this the case?

The formula I am using right now for calculating tape size is as follows:
        I use the tape size written on the cassette with no safety margin!
        density = 10000   (thats ten thousand)
        size = 450 feet

My guess is that one of the following formulas is correct:
        (tape size)*((9 tracks)/(8 tracks))*(safety factor)

        (tape size)*(safety factor)

where (safety factor) is something like 0.9 or 0.94 (depending on who
you talk to).
Johan Widen
SICS, PO Box 1263, S-163 13 SPANGA, SWEDEN


QIC-11, QIC-24 and dump(8) tape length

Post by Craig Ler » Thu, 02 Aug 1990 21:35:00

This is a question I recently answered on comp.sys.sun.

The QIC-24 format makes 9 passes over the tape. The general formula
for figuring out how many feet of tape dump can use is:

        dump_tape_length = (actual_tape_length - 25) * no_of_passes

So when doing dumps, you should use something similar to one of the

        dump 0uncbsf 126 2475 /dev/rst8 /mnt    # QIC-24, 300 foot tape
        dump 0uncbsf 126 3825 /dev/rst8 /mnt    # QIC-24, 450 foot tape
        dump 0uncbsf 126 5175 /dev/rst8 /mnt    # QIC-24, 600 foot tape

QIC-11 only makes 4 passes:

        dump 0uncbsf 126 1100 /dev/rst0 /mnt    # QIC-11, 300 foot tape
        dump 0uncbsf 126 1700 /dev/rst0 /mnt    # QIC-11, 450 foot tape
        dump 0uncbsf 126 2300 /dev/rst0 /mnt    # QIC-11, 600 foot tape

I think the recent consensus is that a block size of 126 is optimal.



1. QIC-24 format tapes (qic-02 and qic-36 interface)

I'm looking for any information/drivers for qic-02 controllers and the
qic-24 format tapes.  I've been able to get the driver under Linux
(1.2.13) compiled, but without a formated tape to test it, I can't
verify if I got everything working or not.

Problem: I've no dos software to format a DC-600A tape in the drive.
Failing a driver for dos so I format the tapes, I would like the
information on the qic-24 format for the DC-600A tapes so I could
write a format utility for Linux.  Any help would be appreciated.
(a linux format utility would be nice also/instead)

2. List of Solaris 2 - compatible disk drives?

3. Loading OpenBSD from QIC-24 tape on QIC-02 interface

4. Preferred method if starting routed?

5. oops, not qic-02 it's a qic-24

6. Difference between MU4 and patch cluster ?

7. WTB/WTTF:NetBSD for Sun 3/60 on bootable QIC-24 tape

8. can't seem to compile functional .so libs

9. QIC-24 tape drive?

10. Wangtek 5150 QIC-24 write pb

11. QIC-36 tape drive with an Emulex QIC-36-> SCSI board

12. wanted information on QIC-40/QIC-80 tape drives.

13. Need Help w/ using SCSI QIC drive to read tapes from floppy QIC