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We have had to do data recovery from the 23 megabyte cartridge tape drives as found on the older 3B2/400 family of computers, and we got tired of dragging out the /400 when we needed to do this. So we decided to move the whole thing to the 3B2/600. These are the steps we took in case you care to do this yourself.
First, install the CTC software. This can be done without the card being installed, and doing it first saves one reboot later. This is done by the usual sysadm installpkg, and the software is installed into the usual places. You'll be asked two questions: answer "no" to whether your unit contains an XM disk drive, and "yes" to whether it contains a tape drive.
Note the last few device names (like /dev/rSA/ctape1), then power down the system.
Next, mount the CTC I/O card (CM195H) into the next open slot in the 3B2, and there is a single connector on it for the ribbon cable. It's organized in a way that the cable can route outside or inside the cabinet, and for temporary use it's probably easiest to run the cable outside. Fortunately, the cable provided by the 3B2/400 is quite long.
In the past we've found an old disk drive case to park the tape drive in, mainly just to receive power, and the cable runs from the 3B2 to the tape drive. This is not very pretty, but it's more than enough to do the job for a quick data transfer job.
We do this transfer often enough that we went the "fancy" route of cutting an extra hole in the front panel of the main unit to expose the tape drive to the outside and mounted the whole thing internally. It's much more work, but very neat and permanent. Probably more reliable too.
Power on the tape drive (if external), then the machine. It should pass diagnostics and rebuild the /unix kernel automatically. Boot multiuser.
Now the drive is installed, and though there are many device names for it, the one that matters is /dev/rSA/ctape1. Note the name ctape is for cartridge tape drives, and qtape is for SCSI tape drives.
These 23MB tape drives are "Floppy Tape" units, which mean they look in hardware and like a floppy drive (!), but they can still be used to back up a system normally. The CTC utilities come with a utility ctccpio for talking to this drive, but it's not necessary: this program puts the drive in "steaming" mode which reportedly can run much faster, but we generally don't use it: standard cpio works just fine.
The first step in processing a tape is to check the table of contents, and this is done with the cpio command:
# cpio -itvcBI/dev/rSA/ctape1
This gives a listing of the files on the tape, but doesn't actually read any of the data on to the disk. This will let you figure out just what's on the tape and if it's even the one you're looking for.
To actually read the data, you go to the top of the directory tree where you wish to restore the data and issue the command:
# cd /tmp # cpio -idmucvBI/dev/rSA/ctape1
This reads each file into /tmp (and below), and shows each filename as it's being restored.
Warning - if the filenames on the tape all begin with a slash, it means that you can only restore the files to that location on the disk - no "relative" loads. This is why we recommend never to use absolute paths when backing up data.