[TUHS] Unix v7 tape drive question

[TUHS] Unix v7 tape drive question

[KenUnix]

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Hi,

I am trying to use the 'dump' program but it references rmt1.

My system only has rmt0. I have been unable to find how to
create this device. I have looked over the reference material
but it only references rmt0.

Is there any way to redirect a dump to use rmt0?

Any help is appreciated.

# ls -l
total 4
drwxr-xr-x 2 root      336 Mar  1 16:56 .
drwxr-xr-x 8 root      288 Feb 21 17:18 ..
crw--w--w- 1 root    0,  0 Mar  2 07:47 console
crw-r--r-- 1 bin     8,  1 Jan 10  1979 kmem
-rw-rw-r-- 1 bin       775 Jan 10  1979 makefile
crw-r--r-- 1 bin     8,  0 Jan 10  1979 mem
*brw-rw-rw- 1 root    3,  0 Mar  1 20:42 mt0*
crw-rw-rw- 1 root   12,128 Dec 31  1969 nrmt0
crw-rw-rw- 1 bin     8,  2 Dec 31  1969 null
*crw-rw-rw- 1 root   12,  0 Feb 23 15:55 rmt0*
brw-r--r-- 1 root    6,  0 Mar  2 07:47 rp0
brw-r--r-- 1 root    6, 15 Dec 31  1969 rp3
crw-r--r-- 1 root   14,  0 Dec 31  1969 rrp0
crw-r--r-- 1 root   14, 15 Dec 31  1969 rrp3
brw-r--r-- 1 root    6,  1 Dec 31  1969 swap
crw-rw-rw- 1 bin    17,  0 Mar  1 19:39 tty
crw--w--w- 1 root    3,  0 Mar  1 19:41 tty00
crw--w--w- 1 root    3,  1 Feb 23 16:47 tty01
crw--w--w- 1 root    3,  2 Feb 21 16:56 tty02
crw--w--w- 1 root    3,  3 Feb 21 16:56 tty03

Not only that but when attempting to use dump it creates
a file and consumes all the space on rp0

In dev it creates:

-rw-rw-r-- 1 root   174080 Mar  2 09:20 rmt1

Sample run:

# dump
     date = Thu Mar  2 09:20:16 2023
dump date = the epoch
dumping /dev/rrp3 to */dev/rmt1*
I
II
estimated 24870 tape blocks on 0 tape(s)
III
IV
*no space on dev 6/0*
no space on dev 6/0
no space on dev 6/0
no space on dev 6/0

Thanks,
Ken

-- 
WWL 📚

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[TUHS] Re: Unix v7 tape drive question

[Dan Cross]

On Thu, Mar 2, 2023 at 9:28 AM KenUnix <ken.unix.guy@gmail.com> wrote:
> I am trying to use the 'dump' program but it references rmt1.
>
> My system only has rmt0. I have been unable to find how to
> create this device. I have looked over the reference material
> but it only references rmt0.
>
> Is there any way to redirect a dump to use rmt0?
>
> Any help is appreciated.

I'd start with the man page.

Dump(1M) says that argument `f` causes `dump` to, "Place the dump on
the next argument file instead of the tape". Did you try using that
option with `/dev/rmt0`?

Alternatively, I don't see why you couldn't hard-link /dev/rmt1 to /dev/rmt0:

# cd /dev
# ln rmt1 rmt0

Or use `mknod` to create a device file with the same major/minor numbers:

# cd /dev
# /etc/mknod rmt1 c 12 0

Or even, as a very last resort, edit the source and change the default
dump device.  It's in /usr/src/cmd/dump.c

Hope that helps!

        - Dan C.

[TUHS] Re: Unix v7 tape drive question

[KenUnix]

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Dan,

Thanks, that did the trick.

# dump
     date = Thu Mar  2 09:52:02 2023
dump date = the epoch
dumping /dev/rrp3 to /dev/rmt1
I
II
estimated 24870 tape blocks on 0 tape(s)
III
IV
level 9 dump on Thu Mar  2 09:52:02 2023
DONE
25228 tape blocks on 1 tape(s)

And, I will change dump.c and dumpdir.c to use tm0.

Ken


On Thu, Mar 2, 2023 at 9:40 AM Dan Cross <crossd@gmail.com> wrote:

> On Thu, Mar 2, 2023 at 9:28 AM KenUnix <ken.unix.guy@gmail.com> wrote:
> > I am trying to use the 'dump' program but it references rmt1.
> >
> > My system only has rmt0. I have been unable to find how to
> > create this device. I have looked over the reference material
> > but it only references rmt0.
> >
> > Is there any way to redirect a dump to use rmt0?
> >
> > Any help is appreciated.
>
> I'd start with the man page.
>
> Dump(1M) says that argument `f` causes `dump` to, "Place the dump on
> the next argument file instead of the tape". Did you try using that
> option with `/dev/rmt0`?
>
> Alternatively, I don't see why you couldn't hard-link /dev/rmt1 to
> /dev/rmt0:
>
> # cd /dev
> # ln rmt1 rmt0
>
> Or use `mknod` to create a device file with the same major/minor numbers:
>
> # cd /dev
> # /etc/mknod rmt1 c 12 0
>
> Or even, as a very last resort, edit the source and change the default
> dump device.  It's in /usr/src/cmd/dump.c
>
> Hope that helps!
>
>         - Dan C.
>


-- 
End of line
JOB TERMINATED

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[TUHS] Re: Unix v7 tape drive question

[Clem Cole]

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On Thu, Mar 2, 2023 at 9:28 AM KenUnix <ken.unix.guy@gmail.com> wrote:

> Hi,
>
> I am trying to use the 'dump' program but it references rmt1.
>
> My system only has rmt0. I have been unable to find how to
> create this device. I have looked over the reference material
> but it only references rmt0.
>
> Is there any way to redirect a dump to use rmt0?
>
Some thoughts...

1.) start with the man page: https://man.cat-v.org/unix_7th/1/dump
You note the first key parameter described is f - i.e. dump fu0 /dev/rmtXXX
/dev/rrpY

Remember on traditional research systems like V6/V7you should use rmtX and
rrpY not mtX and rpY as you don't what to use the buffer cache (modern
UNIXs & Linux use the paging HW so things like need for the old I/O buffer
cache are avoided).

2.) next: read: https://man.cat-v.org/unix_7th/4/tm

cd /dev; ls -l *mt*
(if you type: cat makefile that would not hurt)

I suspect you will see three devices: mt0 (a blocked device i.e. thru the
buffer cache and then copied in/out to your program) and two raw devices:
rmt0 and nrmt0 (character devices i.e. direct I/O to your program).    Using
mknod create the next Unit number - i.e. three more device files: mt1 rmt1
and nrmt1   - don't forget chmod them too

Now with simh, you can add:  attach tm1 some_local_file

3.) since you are using simh, you could also use the RH11/RH70 based Tapes
which are the ht devices: https://man.cat-v.org/unix_7th/4/ht
The makefile in dev will create 2 drives for you and make sure you use a
UNIX kernel configured with the ht driver included.
Also in simh, enable TU0 and TU1 instead of TM0 and TM1

I would not recommend recompiling the tape utilities, although as Dan said
you could do that.


ᐧ

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