SCSI tape drives on a Mac...

[massey]

Mike:

In my on-going quest to retire my Sun, I've installed a SCSI card in my G5 Mac,
and about to stcik on my DDS4 and Exabyte tape drives. I'd like to be able to use these in IRAF. Any idea if this is going to be easy or hard?

thanks,
phil

[fitz]

"Easy" and "Hard" are such relative terms We've never been asked about tape support in OSX and last I looked there was no/little native framework in the system to support tapes, so I'd lean towards hard on this. You could always just try it using and existing tapecap entry but keep in mind that commandline tools like 'mt' are normally used to debug tapecaps and I don't see that on my system. A lot may depend on the vendor of your scsi card, check their site for drivers and OSX peculiars first and don't even mess with IRAF until you've got the drive working under OSX first. In the worst case, the iraf kernel tape driver may need work, but there are other ways to read/write FITS tapes so long as you can read/write the tape outside of iraf.

Cheers,
-Mike

[massey]

OK, I now know more about this than possibly I wanted to know. Deidre's been looking into this, and here's what we've established. I'm posting this here just in case anyone else is considering this.

a) The ATTOTECH SCSI card apparently has the reputation of being very Mac compatable.
b) But, there are no tape commands in OSX.

Here's what Deidre's wrote:

I now understand tape drives under MacOSX, at least at the level necessary to move forward. The bottom line is: MacOSX does not have any mechanism for doing tapes. It has tar and some other utilities, but these do not know anything about tape drives. You have to have/get an application that can interface between a command like tar and the tape drive.

One such product is the commercially-available TOLIS Tape Tools. The Tools are "a set of utilities that enables the transfer of the contents of any tar, cpio, or pax-formatted tapes onto a Mac OSX system. Regardless of whichever system platform on which the tapes were originally created .. TOLIS Tape Tools supports every tape technology and tape format ... The Tools are also transport layer independent. This ... means no special drivers are needed." Commands are issued on the command line.

Examples:

To rewind the tape: tapectl -f ntape0 rewind
To position the tape forward 2 file marks: tapectl -f ntape0 fsf 2
To read a tar tape: taperead -f ntape0 | tar -xvf -
To write a tar tape: tar -cvf - /users/dah | tapewrite -f ntape0

Note 1: If you type "tapectl display", it searches all busses and reports any type 1 SCSI, Fibre-Channel, Firewire, or USB. They name the devices ntapeX, starting with X=0. The default is X=0, and ntape0 could have been left out of the above commands. They support multiple tape drives.

Note 2: When reading and writing tar tapes, you have to specify the buffer size if it is not the default buffer size of 20. tar on the Suns was able to figure out the buffer size itself.

Note 3: To read or write FITS tapes, you would need to have an application that you could pipe the data into. So, I don't know if this would work with IRAF. However, I have AIPS running and it has tape utilities, including reading FITS tapes, although I haven't tested it yet.