granroth@iowasp.physics.uiowa.edu (Larry Granroth) (06/19/91)
I'm looking for a good source for 60 meter *data certified* 4mm DAT tapes. So far, we've had good luck with Sony DG-60M data certified tapes, but I'd be willing to try TDK or Maxell (or other brands with a convincing recommendation). I'd prefer a vendor that can ship us a batch of about 15 for evaluation, after which our typical order would be 50 to 100 every few months. APUNIX used to ship Maxell data certified DATs in small quantities from stock for $13 each (but have recently raised the price to $15), so that's our price target. There has been a fair ammout of discussion recently on the reliability of the DAT media. From what I've gathered, talking with people at JPL, U of Arizona, and Maynard/Archive, 4mm DAT is one of the most reliable tape formats available. There is no significant possibility for "print through" and no evidence of any other systematic problem. We have found occasional bad tapes when trying to use consumer/audio DAT tapes, but have had no difficulty with several hundred data certified (properly tested) cartridges. While we were doing some spacecraft component tests we took the opportunity to do some (what might be "accelerated life") DAT tests. We wrote a known test pattern (56 files, 52120 variable-length records, 1001806780 bytes) on a tape, then read it 8 times without any errors (checking every bit) to verify the tape and test the software. Next, we baked the tape at 40C for three days and read it 8 times again without any errors. After this, we temperature cycled the tape from -30C to +60C for 5 cycles at 1C per minute and then read it 12 times without any errors. This test of one tape doesn't have much statistical significance, but it was sufficient for us to decide to use the DDS DAT media for some of our new spacecraft data projects that will be generating over 1GB of data per day after launch. Thanks in advance for vendor leads. If you have any additional DAT tape reliability experiences, I'd be interested in hearing about those too. -Larry Granroth@IowaSP.physics.UIowa.edu IOWASP::GRANROTH