From owner-freebsd-scsi Mon Feb 10 05:53:07 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id FAA03565 for freebsd-scsi-outgoing; Mon, 10 Feb 1997 05:53:07 -0800 (PST) Received: from mercury.ukc.ac.uk (mercury.ukc.ac.uk [129.12.21.10]) by freefall.freebsd.org (8.8.5/8.8.5) with SMTP id FAA03560 for ; Mon, 10 Feb 1997 05:53:03 -0800 (PST) Received: from crane.ukc.ac.uk by mercury.ukc.ac.uk with SMTP (PP); Mon, 10 Feb 1997 13:52:40 +0000 Received: from localhost by crane.ukc.ac.uk (SMI-8.6/UKC-2.14) id NAA25556; Mon, 10 Feb 1997 13:52:34 GMT Date: Mon, 10 Feb 1997 13:52:34 +0000 (GMT) From: "K.R.Marshall" X-Sender: krm2@crane To: Joerg Wunsch cc: scsi@freebsd.org Subject: Re: Nakamichi 4-disk changers In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-scsi@freebsd.org X-Loop: FreeBSD.org Precedence: bulk On Sat, 8 Feb 1997, J Wunsch wrote: > As K.R.Marshall wrote: > > > This server won't go online for a couple of weeks so if anyone wants me to > > test out CD-ROM changer code I'll be happy to oblige. > > I've got a Nakamichi 7-disk changer here for testing. The biggest > problem i found (after fixing the ``Logical unit is in the process of > becoming ready'' problem) is that the drives are likely to go > thrashing on concurrent access, since the kernel doesn't lock one > medium in a device for long enough, so the drives will finally be very > busy constantly swapping their media. The way I will be configuring it the swapping shouldn't be too much of a problem. This won't be a "full" networked server in he normal sense. It's more of a general repository for CDs away from the public - each CD will only ever be accessed by one machine at a time so I should be able to avoid heavy swapping by judiciously arranging the CDs in the changers. I wouldn't yet consider such a system for a full CD-ROM network, but hopefully FreeBSD will support such things in a better way at some point in the future..? I understand there are now NT-based systems which deal intelligently with the problems of changers (i.e. with cacheing etc..) Currently we just use normal stacks of CD-ROM drives and a large 9Gb hard disk with several packages copied to it for faster access (all hanging off a FreeBSD box, of course..). Keith. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "Mummy was an asteroid, Daddy was a | Keith Marshall small, non-stick kitchen utensil..." | Computing Officer, Templeman Library - Quiet Sun, 1975 | University of Kent at Canterbury.