How can I uninstall ioscsitape?

[Paul Stone]

Hi,

I'm not very familiar with the Mac. I installed ioscsitape in order
to do some simple 'dd' commands from a tape drive. The 'dd' commands
don't seem to work, and so I want to uninstall ioscsitape, and lo and
behold, I have no idea how to do that.

Here's what I get for the 'dd' commands:

$ dd if=/dev/rst0 count=3 of=junk
dd: /dev/rst0: Function not implemented
0+0 records in
0+0 records out
0 bytes transferred in 0.005315 secs (0 bytes/sec)

I think I may be getting the "Function not implemented", because it's
hitting a filemark, but I'm able to gradually read into the tape, and
I can never get any file data off of the tape:

$ mt -f /dev/rst0 status
SCSI tape drive, residual=0
ds=1<>
er=1<>
blocksize: 0 (0, 0, 0, 0)
density: 0 (0, 0, 0, 0)
current file number: 5
current block number: 0

Could you please let me know how I can uninstall ioscsitape, because
it's interfering with another application.

[Paul Stone]

I think I found out how to uninstall:

http://superuser.com/questions/385/how-to-uninstall-and-remove-a-kext-on-mac-os-x

But, maybe someone has a suggestion regarding why I can't read off of
the tape with 'dd'? I am using a SAS LTO tape drive connected to a
relatively new Mac Pro.

-Paul

[Jesse Peterson]

Hello Paul,

Replies inline:

On Mon, 25 Apr 2011 18:51:28 -0700 (PDT)
Paul Stone <pst...@gmail.com> wrote:

> I think I found out how to uninstall:
>
> http://superuser.com/questions/385/how-to-uninstall-and-remove-a-kext-on-mac-os-x

Indeed, unloading the KEXT (using kextunload) and removing it suffice as an uninstall. Or removing the KEXT and rebooting should work.

> But, maybe someone has a suggestion regarding why I can't read off of
> the tape with 'dd'? I am using a SAS LTO tape drive connected to a
> relatively new Mac Pro.

What do the logs say? (/var/log/system.log and /var/log/kernel.log). When you connect the drive does it report the model and what-not?

More below:

> On Apr 25, 6:42 pm, Paul Stone <pst...@gmail.com> wrote:
> > Hi,
> >
> > I'm not very familiar with the Mac.  I installed ioscsitape in order
> > to do some simple 'dd' commands from a tape drive.  The 'dd' commands
> > don't seem to work, and so I want to uninstall ioscsitape, and lo and
> > behold, I have no idea how to do that.
> >
> > Here's what I get for the 'dd' commands:
> >
> > $ dd if=/dev/rst0 count=3 of=junk
> > dd: /dev/rst0: Function not implemented
> > 0+0 records in
> > 0+0 records out
> > 0 bytes transferred in 0.005315 secs (0 bytes/sec)
> >
> > I think I may be getting the "Function not implemented", because it's
> > hitting a filemark, but I'm able to gradually read into the tape, and
> > I can never get any file data off of the tape:
> >
> > $ mt -f /dev/rst0 status
> > SCSI tape drive, residual=0
> > ds=1<>
> > er=1<>
> > blocksize: 0 (0, 0, 0, 0)
> > density: 0 (0, 0, 0, 0)
> > current file number: 5
> > current block number: 0

It looks like you're using variable blocking mode (0 blocksize). THis is the least tested functionality. I would suggest setting the block size to something like 128k. (hopefully your source data was written with static block size?) It's also odd that the density code is 0--that would seem to indicate the SCSI pages aren't getting read correctly.

$ mt -f /dev/rst0 blocksize 131072

$ mt -f /dev/rst0 status

$ mt -f /dev/rst0 rewind
$ dd .....

And of course check the logs. See if those commands work and let me know!
- Jesse

--
Jesse Peterson <jpeter...@comcast.net>