From owner-freebsd-hackers Sun Feb 4 14:42:21 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id OAA12226 for hackers-outgoing; Sun, 4 Feb 1996 14:42:21 -0800 (PST) Received: from phaeton.artisoft.com (phaeton.Artisoft.COM [198.17.250.211]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id OAA12221 for ; Sun, 4 Feb 1996 14:42:17 -0800 (PST) Received: (from terry@localhost) by phaeton.artisoft.com (8.6.11/8.6.9) id PAA08330; Sun, 4 Feb 1996 15:39:18 -0700 From: Terry Lambert Message-Id: <199602042239.PAA08330@phaeton.artisoft.com> Subject: Re: FAT filesystem performance To: faulkner@asgard.bga.com (Boyd Faulkner) Date: Sun, 4 Feb 1996 15:39:17 -0700 (MST) Cc: luigi@labinfo.iet.unipi.it, hackers@FreeBSD.org In-Reply-To: <199602041854.MAA07227@asgard.bga.com> from "Boyd Faulkner" at Feb 4, 96 12:54:52 pm X-Mailer: ELM [version 2.4 PL24] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hackers@FreeBSD.org Precedence: bulk > Before Terry has a fit :-) , let me tell you what he once told me. > One of the problems of implementing someone else's file system is > error recovery. If you cache FAT and your power goes out, for example, > the FAT on the disk is not consistent. Aside from there being no fsck_msdos, > if you then booted up in DOS, your filesystem would be inconsistent, and > DOS doesn't like or expect that. You can write a fast read-only FAT > FS but you have to fail as FAT would fail, to be truly compatible. > > Did I get that right, Terry? :-) Mostly. If you had delayed ordered writes, the cache could be write-through, so it would work. Then the problems become "no msdos_fsck" and "must order regular I/O" and "cache in MACH is too large". Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.