Can user overwrite to a ignite tape left in the 4mm internal tape drive

[Geetha Alagappan]

I do a make_tape_recovery every 2 weeks and have sometimes left the tape in the 4mm drive. If a user did a tar to default - wouldn't he overwrite my boot image on tape? Seems scary.

Thanks.


Geetha.

[A. Clay Stephenson · Accepted solution]

Yes, assuming the user has write permission to the tape device. It's not scary; it's just UNIX. UNIX expects the user to know what he's doing.

[John Poff]

Hi,

It could happen. If you forget to eject the tape manually or if you run the make_tape_recovery automatically, you could eject the tape with a software command like this:

mt -f /dev/rmt/0m offl

JP

[Ross Zubritski]

Geetha,

The short anwswer is YES!

Regards,

RZ

[Patrick Wallek]

Yes, that is exactly what would happen.

That is why I do a 'mt -f /dev/rmt/?mn offl' to rewind the tape and eject it after the make_tape_recovery finishes. That way no one can "accidentally" overwrite the tape.

That also forces you, or someone, to look at the tape drive and put the tape back in before the next make_tape_recovery. That way you can make sure that the drive doesn't need cleaning.

I would also hope that you aren't using the same tape time after time. I would recommend that you use at least 2 different tapes, preferably more, and keep some offsite somewhere. If something happened to your computer room then you would still want those other make_tape_recovery tapes available for DR purposes.

[Geetha Alagappan]

Thanks guys for the prompt response. Patrick and Kurt - thx for providing me with a solution so that I don't accidentally let a user overwrite it.

I do use 2 sets and alternate between them.

Geetha.

[John Bolene]

Yup, all user has to do is a

mt rw

and then start writing.

I do like that suggestion to eject the tape, I did not know that command existed.

I learnt something from this also.

[Geetha Alagappan]

I added the statement to rewind and eject tape after making an ignite tape. But out of curiosity, is there a way to prevent the user from making writing to the 4mm tape. Is it even worth messing around with this? Thx.
Geetha

[Patrick Wallek]

I haven't tried this, but the only thing I can think of is to just change the permissions on the /dev/rmt/* files so that they are read/write for the user root and group sys only.

[A. Clay Stephenson]

You can change the permissions to restrict access to the tape device - make sure that you change both the long and short versions of the names of all the device nodes associated with that physical device.

Even rewinding and ejecting is not foolproof; the fool can always walk over and re-insert the medium.

If regular users have a legitmate need to write to the tape device then things get more complicated. Probably the most fool-proof method is to install another tape device with open permissions and the original is only writable by root - of course, if the fool is 'root' then you are still in trouble.

[V. Nyga]

Hi Geetha,

take away write permission to the devices in /dev/rmt.
'chmod o-w /dev/...' for 'others'

Regards
Volkmar

[Geetha Alagappan]

Patrick - Clay & Volkmar,
Thx. I think I am all set.
Geetha.