Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750767AbWAOVfH (ORCPT ); Sun, 15 Jan 2006 16:35:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750775AbWAOVfH (ORCPT ); Sun, 15 Jan 2006 16:35:07 -0500 Received: from pne-smtpout2-sn1.fre.skanova.net ([81.228.11.159]:13050 "EHLO pne-smtpout2-sn1.fre.skanova.net") by vger.kernel.org with ESMTP id S1750767AbWAOVfF (ORCPT ); Sun, 15 Jan 2006 16:35:05 -0500 To: Jan Engelhardt Cc: Damian Pietras , Phillip Susi , linux-kernel@vger.kernel.org Subject: Re: Problems with eject and pktcdvd References: <20060115123546.GA21609@daper.net> <43CA8C15.8010402@cfl.rr.com> <20060115185025.GA15782@daper.net> <43CA9FC7.9000802@cfl.rr.com> <20060115210443.GA6096@daper.net> From: Peter Osterlund Date: 15 Jan 2006 22:34:59 +0100 In-Reply-To: Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1969 Lines: 46 Jan Engelhardt writes: > >> pktsetup 0 /dev/hdc > >> mount /dev/pktcdvd/0 /mnt/tmp > >> umount /mnt/tmp > > A question BTW; I do not seem to need pktcdvd for DVD+RWs, > I can just mount them after mkfs'ing /dev/hdc - what's up with that? Basically, if you don't use the packet writing driver, the DVD drive firmware will do similar work on its own, because the hardware can only write 32KB blocks. The firmware is often slower than the pktcdvd driver, because the firmware doesn't have as much memory available as the kernel to reorder I/O operations for improved throughput. See also Documentation/cdrom/packet-writing.txt: Packet writing for DVD+RW media ------------------------------- According to the DVD+RW specification, a drive supporting DVD+RW discs shall implement "true random writes with 2KB granularity", which means that it should be possible to put any filesystem with a block size >= 2KB on such a disc. For example, it should be possible to do: # dvd+rw-format /dev/hdc (only needed if the disc has never been formatted) # mkudffs /dev/hdc # mount /dev/hdc /cdrom -t udf -o rw,noatime However, some drives don't follow the specification and expect the host to perform aligned writes at 32KB boundaries. Other drives do follow the specification, but suffer bad performance problems if the writes are not 32KB aligned. Both problems can be solved by using the pktcdvd driver, which always generates aligned writes. # dvd+rw-format /dev/hdc # pktsetup dev_name /dev/hdc # mkudffs /dev/pktcdvd/dev_name # mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime -- Peter Osterlund - petero2@telia.com http://web.telia.com/~u89404340 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/