Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261378AbUDWU6c (ORCPT ); Fri, 23 Apr 2004 16:58:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261421AbUDWU6b (ORCPT ); Fri, 23 Apr 2004 16:58:31 -0400 Received: from chaos.analogic.com ([204.178.40.224]:14208 "EHLO chaos.analogic.com") by vger.kernel.org with ESMTP id S261378AbUDWU62 convert rfc822-to-8bit (ORCPT ); Fri, 23 Apr 2004 16:58:28 -0400 Date: Fri, 23 Apr 2004 16:59:02 -0400 (EDT) From: "Richard B. Johnson" X-X-Sender: root@chaos Reply-To: root@chaos.analogic.com To: =?iso-8859-1?q?M=E5ns_Rullg=E5rd?= cc: linux-kernel@vger.kernel.org Subject: Re: File system compression, not at the block layer In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2560 Lines: 64 On Fri, 23 Apr 2004, [iso-8859-1] M?ns Rullg?rd wrote: > "Richard B. Johnson" writes: > > > On Fri, 23 Apr 2004, Joel Jaeggli wrote: > > > >> On Fri, 23 Apr 2004, Paul Jackson wrote: > >> > >> > > SO... in addition to the brilliance of AS, is there anything else that > >> > > can be done (using compression or something else) which could aid in > >> > > reducing seek time? > >> > > >> > Buy more disks and only use a small portion of each for all but the > >> > most infrequently accessed data. > >> > >> faster drives. The biggest disks at this point are far slower that the > >> fastest... the average read service time on a maxtor atlas 15k is like > >> 5.7ms on 250GB western digital sata, 14.1ms, so that more than twice as > >> many reads can be executed on the fastest disks you can buy now... of > >> course then you pay for it in cost, heat, density, and controller costs. > >> everthing is a tradeoff though. > >> > > > > If you want to have fast disks, then you should do what I > > suggested to Digital 20 years ago when they had ST-506 > > interfaces and SCSI was available only from third-parties. > > It was called "striping" (I'm serious!). Not the so-called > > RAID crap that took the original idea and destroyed it. > > If you have 32-bits, you design an interface board for 32 > > disks. The interface board strips each bit to the data that > > each disk gets. That makes the whole array 32 times faster > > than a single drive and, of course, 32 times larger. > > For best performance, the spindles should be synchronized too. This > might be tricky with disks not intended for such operation, of course. Actually not. You need a FIFO to cache your bits into buffers of bytes anyway. Depending upon the length of the FIFO, you can "rubber-band" a lot of rotational latency. When you are dealing with a lot of drives, you are never going to have all the write currents turn on at the same time anyway because they are (very) soft-sectored, i.e., block replacement, etc. Your argument was used to shout down the idea. Actually, I think it was lost in the NIH syndrome anyway. > > -- > M?ns Rullg?rd > mru@kth.se > Cheers, Dick Johnson Penguin : Linux version 2.4.26 on an i686 machine (5557.45 BogoMips). Note 96.31% of all statistics are fiction. - 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/