coppi@karl.tapir.Caltech.EDU (Paul Coppi) (10/15/89)
Hi, We recently acquired a DECstation 3100 with an 8mm Exabyte tape drive. Unfortunately, we cannot get the Exabyte to work satisfactorily. The tape drive can reliably read in data from tapes written on Exabytes connected to other machines (Sun 3,4s), but it appears to drop bytes when trying to do a write. Specifically, a byte appears to be dropped every 200-500k of output. The exact locations of the dropped bytes appears to be random. (Repeating exactly the same sequence of commands, the errors occur in different places.) No error messages show up while doing the write, but the file on tape is definitely corrupted. Tar, for example, will give checksum errors when you try to read the file back in. I have also done a dump straight to the device using "cat bigfile > /dev/rmt0h". Reading the file in with "cat < /dev/rmt0h > bigfile.out" and doing a "cmp -l bigfile.out bigfile" gives the same answer (the files differ) when the Exabyte connected to the DECstation is used or an Exabyte connected to a Sun is used. I've tried this with several tapes (in case one of them was bad). We have reported the problem to our vendor (Computer Systems Technologies in El Toro, CA), but they didn't have anything useful to say. Any ideas?? We would like to know if someone else out there is using an Exabyte to write large files and has experienced similar problems. Could you please tell us exactly what your system configuration is, what ROM revision level your Exabyte is (if your machine is halted, you can print it out by typing "test -c<ret>" after the console monitor prompt ">>"), and what programs you have successfully/unsuccessfully used your Exabyte with. Does any one know of a preferred blocking size for the Exabyte? It could well be that our drive is faulty. (If we get lots of "Yes, our Exabyte works" responses, we'll ship ours back to the vendor.) However, given the problems people have had getting Exabytes to run with Suns, something deeper may be wrong. Our system configuration is as follows: 1 12 MB DS3100, 2 CDC WREN V disks, 1 Exabyte with ROM revision level 4.24. We are running Ultrix 3.1, and the Exabyte is recognized as SCSI device #4, type "TZxx". Thanks in advance for any help you might be able to give, Paolo Coppi Theoretical Astrophysics, Caltech coppi@tapir.caltech.edu, coppi@zeppo.caltech.edu