John Ruschmeyer <jruschme(a)hiway1.exit109.com> wrote: 3M used to sell the 15MB/150-foot 9144-compatible flavor as the DC615HC. A former employer tried to get me to use those once, which is how I found this out. After trying one for a while, I declined. Here's why: There are two or three layers of "formatting" on these. The 3M tapes had the lowest layer, the one that must be done at the factory because it requires the full-width head that can write block delimiters. The HP tapes have the next layer as well, the data that is read by the tape drive and which contains usage and block sparing information. If you have an HP3000 w/9144 the VINIT FORMAT command will write this, but in my experiments at the former employer I found it took noticeably longer to format the 3M tapes (perhaps it was testing the tape blocks to figure out which blocks need sparing? I don't know). I didn't think it was worth the couple of bucks we would save per tape for someone to sit on his or her butt waiting for this to happen. But once you do this they do work. And I have no idea how to do this step with a 9000. The third layer? Well, on a 3000 you access the 9144 as though it is a removable-pack disc drive. Fortunately the 3000 has the concept of accessing a disc serially: you use the VINIT SERIAL command to label the "disc" (actually the tape) as a serial volume. I don't think this applies to 9000s but I think for the 9000s you are supposed to pipe tape data through tcio (which buffers the tape drive I/O in a way that reduces wear and tear on the drive and tape). -Frank McConnell