Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!sun-barr!decwrl!sgi!shinobu!odin!anchor!olson From: olson@anchor.esd.sgi.com (Dave Olson) Newsgroups: comp.sys.sgi Subject: Re: Media error on Exabyte Keywords: Exabyte Message-ID: <1990Nov2.003444.4650@odin.corp.sgi.com> Date: 2 Nov 90 00:34:44 GMT References: Sender: news@odin.corp.sgi.com (Net News) Distribution: comp Organization: Silicon Graphics, Inc. Mountain View, CA Lines: 50 In muenzel@wega.tat.physik.uni-tuebingen.de (Stefan Muenzel) writes: | Once more a problem with the EXA-Byte: | We have a EXA-Byte 8200 and want to use it with a SGI 4D/20. | But when we try to tar some bytes we get messages like the following: | | Oct 22 18:05:04 mira unix: NOTICE: SCSI tape #5 Uncorrectable media error | Oct 22 18:05:04 mira unix: NOTICE: SCSI tape #5 Unrecoverable error | Oct 22 18:05:04 mira unix: NOTICE: SCSI tape #5 had 2215 recoverable Errors | | (Copied from the SYSLOG-file). | This occures after some 100 kbytes. Our first guess was, that we had | bad tapes, but we've tried several new ones from Sony and Exabyte. It | seems not to be a problem of the SCSI-bus. The message indicates that the Exabyte returned a check-condition on a write, then returned 'media error' as the specific error type. The recoverable error message indicates that there were a LOT of errors that were recovered from by retries. If all this happens in 100 Kbytes, then I see several possiblities: 1) your heads need cleaning. Get the dry (not wet) cleaning kit and clean the heads. This can make a big difference. Remember that the heads should be cleaned on a regular basis, and more often when using new tapes, since they tend to shed more coating. 2) Get certified data tapes if 1) doesn't work. In any case, we have been told by Exabyte tech people to avoid Maxell and TDK, (as of a year OK; the situation may have changed since then) and to NOT use MP (metal particle) tapes. Sony tapes seem to work pretty well (which isn't surprising, since they make the Exabyte Data tapes). A number of other brands seem to work OK also. 3) Watch your recovered error rate. I typically see a few hundred for multi-Mb archives. Whatever your rates are, keep an eye on them, and clean the heads when the error rate rises, or if you are trying new tapes, don't use that brand/type if they consistently return higher error rates. The recovered errors are reported on close of the tape if the tape was read or written (or other commands that moved the tape were used). Typically the counter is reset only when the tape is unloaded. -- Dave Olson Life would be so much easier if we could just look at the source code.