Received: (from majordomo@localhost) by oss.sgi.com (8.11.2/8.11.3) id f67BVxJ27032 for linux-xfs-outgoing; Sat, 7 Jul 2001 04:31:59 -0700 Received: from horus.its.uow.edu.au (horus.its.uow.edu.au [130.130.68.25]) by oss.sgi.com (8.11.2/8.11.3) with SMTP id f67BV2V26831 for ; Sat, 7 Jul 2001 04:31:02 -0700 Received: from uow.edu.au (wumpus.its.uow.edu.au [130.130.68.12]) by horus.its.uow.edu.au (8.9.3/8.9.3) with ESMTP id VAA21930; Sat, 7 Jul 2001 21:30:53 +1000 (EST) Message-ID: <3B46F34D.2744AF68@uow.edu.au> Date: Sat, 07 Jul 2001 21:32:29 +1000 From: Andrew Morton X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.4.6 i686) X-Accept-Language: en MIME-Version: 1.0 To: Jens Axboe CC: Steve Lord , Andrew Klaassen , linux-xfs@oss.sgi.com Subject: Re: More on write caching References: <20010706130636.C2814@dkp.com> <200107061738.f66Hcpb09219@jen.americas.sgi.com> <3B469DDF.905AEC0B@uow.edu.au>, <3B469DDF.905AEC0B@uow.edu.au> <20010707131328.F16505@suse.de> <3B46F0E5.77EAF1F9@uow.edu.au>, <3B46F0E5.77EAF1F9@uow.edu.au> <20010707132238.G16505@suse.de> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-xfs@oss.sgi.com Precedence: bulk Jens Axboe wrote: > > > Question is: does IDE need it at all? If we can assume > > that the data is safe once the drive has acked it, then that's > > all a journalling fs cares about, yes? > > It would enable safe use of write caching, so yes. For a barrier write, > do a sync flush following a write/write_dma/write_dma_queued command > (yes dma_queued has no ordered/sync option, yay ide). There was some discussion a while back, (triggered by someone's benchmark where IDE was thrashing SCSI) where it turned out that some IDE disks were simply ignoring the flush command. Which is a quite sane thing to do if the write cache integrity is guaranteed in this manner. What's the story with other storage interfaces apart from SCSI? Seems that most of them implement SCSI in some way anyway - are there other technologies that need thinking about?