Date: Tue, 5 Mar 1996 18:28:39 +0100 From: se@zpr.uni-koeln.de (Stefan Esser) To: "Justin T. Gibbs" <gibbs@freefall.freebsd.org> Cc: freebsd-scsi@freefall.freebsd.org, freebsd-hardware@freefall.freebsd.org, freebsd-hackers@freefall.freebsd.org Subject: Re: Archive Anconda Tape drive 1.35GB Message-ID: <199603051728.AA00074@Sysiphos> In-Reply-To: "Justin T. Gibbs" <gibbs@freefall.freebsd.org> "Re: Archive Anconda Tape drive 1.35GB" (Mar 5, 6:38)
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On Mar 5, 6:38, "Justin T. Gibbs" wrote: } Subject: Re: Archive Anconda Tape drive 1.35GB } >When operating as a SCSI-2 device (jp6 shorted) the drive does not } >lock the scsi bus during the operations listed above. However to } >get the ncr working with /sbin/dump, the ncr requires a patch } >extending the latetime from 10 secs to a larger value. presently } >i am using 20 minutes. ;( but it works and its fast! it does } >not lock the bus while the dump is being written to tape. } } What does the latetime value affect? The NCR updates a time variable whenever it passes a certain point in its main program loop. Once per second the driver checks the last update time of this variable, and issues a NCR start, if it hasn't been updated for more than a few seconds (this restart doesn't affect normal operation, it is a NOP if the controller is connected to some device). If the watchdog code finds the time variable has not been updated for "latetime" seconds, it assumes a severe fault and tries to reinitialize the NCR chip and the driver. This leads to much confusion, if the SCSI bus was locked for many minutes because of a tape not disconnecting on rewind ... I might remove this watchdog timer, since it seems to cause more problems than it solves (i.e. I don't know, whether it ever was triggered for its designed purpose) ... Regards, STefan -- Stefan Esser, Zentrum fuer Paralleles Rechnen Tel: +49 221 4706021 Universitaet zu Koeln, Weyertal 80, 50931 Koeln FAX: +49 221 4705160 ============================================================================== http://www.zpr.uni-koeln.de/~se <se@ZPR.Uni-Koeln.DE>
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