Date: Tue, 11 Dec 2001 01:43:18 +0000 From: Tony <tony@ubik.demon.co.uk> To: freebsd-hackers@freebsd.org Subject: Re: [SUGGESTION] - JFS for FreeBSD Message-ID: <7UAeNSA2SWF8Iwe5@ubik.demon.co.uk> In-Reply-To: <20011210195725.A4697@mail.slc.edu> References: <20011210220153.50612.qmail@web21102.mail.yahoo.com> <20011210161410.L92148@elvis.mu.org> <002601c181cb$8c6a5e90$1200a8c0@gsicomp.on.ca> <20011210174711.A3208@mail.slc.edu> <20011210220153.50612.qmail@web21102.mail.yahoo.com> <20011210161410.L92148@elvis.mu.org> <002601c181cb$8c6a5e90$1200a8c0@gsicomp.on.ca> <20011210220153.50612.qmail@web21102.mail.yahoo.com> <20011210174711.A3208@mail.slc.edu> <20011211105617.K63585@monorchid.lemis.com> <20011210195725.A4697@mail.slc.edu>
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In article <20011210195725.A4697@mail.slc.edu>, Anthony Schneider <aschneid@mail.slc.edu> writes >> > perhaps there could be an upgrade to offer >> > options SOFTERUPDATES >> > as an equal-but-different alternative to jfs? >> >> And what would that do? > >My thoughts were that if the two were similar in effect that it might be >a relatively easy project to escalate towards achieving the same effects >in one as the other. I understand that this is not necessarily the case. The philosophies in designing the file systems were quite different. At the abstract these are efficiency versus reliability. The philosophy behind a file system not only guides the structure of code it also shapes the structures on disk. A transaction based or journal file system will, for example, appear to grow a database file by whole valid records. If the change is interrupted and the system is restarted the file will either be on the state it was in before the change or in the state afterwards. The usual efficiency oriented file systems can be interrupted at intermediate points: extra disk space is marked as allocated, disk space is assigned to file, file write has happened but the file length has not been updated (or vice versa). Most current users will probably not like the speed penalties of a journal file system, and stick to the faster FS. On the other hand a solid journal FS may encourage more take up for back end databases, for e-commerce, data warehousing, etc... Tony -- "One needs literature in one's life, because without it one deteriorates." - Nelson Mandela To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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