From owner-freebsd-scsi Thu Jan 2 09:51:55 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.4/8.8.4) id JAA18859 for freebsd-scsi-outgoing; Thu, 2 Jan 1997 09:51:55 -0800 (PST) Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by freefall.freebsd.org (8.8.4/8.8.4) with SMTP id JAA18848 for ; Thu, 2 Jan 1997 09:51:45 -0800 (PST) Received: from sax.sax.de (sax.sax.de [193.175.26.33]) by irz301.inf.tu-dresden.de (8.6.12/8.6.12-s1) with ESMTP id SAA10382 for ; Thu, 2 Jan 1997 18:51:43 +0100 Received: (from uucp@localhost) by sax.sax.de (8.6.12/8.6.12-s1) with UUCP id SAA11968 for freebsd-scsi@FreeBSD.org; Thu, 2 Jan 1997 18:51:43 +0100 Received: (from j@localhost) by uriah.heep.sax.de (8.8.4/8.6.9) id SAA08128 for freebsd-scsi@FreeBSD.org; Thu, 2 Jan 1997 18:47:14 +0100 (MET) From: J Wunsch Message-Id: <199701021747.SAA08128@uriah.heep.sax.de> Subject: Ideas on CD changers sought To: freebsd-scsi@FreeBSD.org (FreeBSD SCSI list) Date: Thu, 2 Jan 1997 18:47:14 +0100 (MET) Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) X-Phone: +49-351-2012 669 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E X-Mailer: ELM [version 2.4ME+ PL17 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-scsi@FreeBSD.org X-Loop: FreeBSD.org Precedence: bulk Something that's on my back-burner for quite some time now: A friend gave me a Nakamichi CD changer some time ago, since its behaviour under FreeBSD is a little undesirable. People probably have seen my recent commits (send the `start unit' command earlier, and retry `device is in the process of becoming ready' forever) which make it work a little better. However, there's still one big problem: concurrent access to the various CDs. Even two processes using two CDs concurrently now cause the device to basically start thrashing: the accesses to the media get intermixed to a degree where the device is finally mostly busy with swapping media, instead of transferring data. Now the $ 9.99 question is: what's the best way to avoid this, so some more transfers will be queued up for one device first, before the LUNs should change? Should this be CD driver specific, or are other drivers also in need for this? -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)