Date: Wed, 22 Oct 1997 15:38:14 -0400 From: Andrew Heybey <ath@bellcore.com> To: scsi@freebsd.org Subject: Re: NCR 53c810 & DAT tape [Solved?] Message-ID: <199710221938.PAA00882@grapenuts.bellcore.com>
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Well, not really solved, but maybe a work-around. I have the Seagate/Conner/Archive DDS-1 DAT drive (Seagate model 4320RT, identifies as "ARCHIVE Python 25501-XXX 5.45") that wedges after writing anywhere from a couple to several hundred MB. I poked around on the Seagate web site and found a page that suggested that their tape drives be run only in asynchronous mode and no faster than 5 MB/s. So first I tried using ncrcontrol to set the drive to be asynchronous ("ncrcontrol -t 6 -s async") but that didn't help. Then, grasping at straws, I tried changing back to synchronous mode but limiting it to 4 MB/s ("ncrcontrol -t 6 -s sync=4"). (When initially probed, the drive claims to do synchronous at 6.7 MB/s.) I then managed to write a whole 60m tape full of zeros (1.3GB) and to do four 300MB dumps in a row without wedging (I also read back two of the dumps), so this may have done it. Any thoughts on whether there is any logical explanation as to why this fix would work when just setting async mode wouldn't? The drive is the only device on the bus and there are terminators on both the controller and the drive. I haven't tried a different cable yet. Now if I can just figure out how to accomplish the equivalent speed limitation under Windoze NT. andrew
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