Problem with the dd command

[Bryan Quinn]

I am using the following command to backup our boot disk before working on the
system next week. I am getting and I/O error. It seems to be reading the boot
disk, I think the problem has something to do with syntax or the tape unit
itself, can someone help?
Here is the command I am using:
dd if=/dev/dsk/c2t11d0 of=/dev/rmt/0mnb bs=1024k
Any thoughts?
Thanks,
Bryan

[Evan Day_1]

Is there a particular reason you're using the no-rewind berkeley tape device?
You might try it with /dev/rmt/0m to see if it makes any difference.

I'm not 100% sure, but this may not work so well if the disk is being accessed
by other processes while the dd is running. I moved some logical volumes
around with dd a while back for a database engine and had to bring the engine
down before it would work. You may need to come up on recovery media or an
alternate boot disk.

I assume you're running this as root. Permissions on device files may or may
not block the operation if you run as an unprivileged user.

-Evan

[Zhang Zhao gui]

I think you may try /dev/rmt/0mn instead of /dev/rmt/0mnb.