Date: Thu, 21 Sep 2000 18:43:05 -0400 (EDT) From: Craig A Soules <soules+@andrew.cmu.edu> To: freebsd-fs@freebsd.org Cc: freebsd-fs <freebsd-fs@FreeBSD.ORG> Subject: Re: Journaling Filesystems in bsd? (LFS, anyone?) Message-ID: <Atmcvty00UwCBkzskM@andrew.cmu.edu> In-Reply-To: <Pine.BSF.4.21.0009211119130.11565-100000@orvieto.eecs.harvard.edu> References: <Pine.BSF.4.21.0009211119130.11565-100000@orvieto.eecs.harvard.edu>
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Excerpts from internet.computing.freebsd.fs: 21-Sep-100 Re: Journaling Filesystems .. by Christopher Stein@eecs.h > On Thu, 21 Sep 2000, Craig A Soules wrote: > > > Excerpts from internet.computing.freebsd.fs: 21-Sep-100 Re: Journaling > > > Log-structured file systems offer different semantics than > > > synchronous journaling file systems. Synchronous journaling can > > > offer the traditional durability of create. Nothing is durable > > > > Wouldn't it be possible to offer the same semantics as FFS in an LFS > > implementation if the segment was (over)written after each operation? > > Partial segment writes? well, that's not quite what I had in mind... I was rather thinking, imagine an async LFS implementation, where you wait to write out each segment until it is full. Instead, do the same thing in memory, but after each operation, also commit that segment to disk. You could end up writing the segment an undefined # of times in a row, but it would give you the same semantics as a sync journaling system, as well as all of the same foreground characteristics of LFS (no additional fragmentation as you hinted at). It seems as though that should be feasable. That way the cleaner wouldn't have additional work (although still all the regular overhead of LFS). craig To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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