Messages in this thread | | | From | "Kevin M. Bealer" <> | Subject | Re: Journalling of Metadata in ext2fs? | Date | Thu, 20 May 1999 01:53:43 -0400 |
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"Stephen C. Tweedie" wrote: >Hi, > >Matthew Kirkwood writes: > > > Linux does not support synchronous metadata, except as a side-effect of > > completely synchronous filesystems. Stephen Tweedie (sct@redhat.com) is > > working on journalling extensions to ext2 and the vfs/block device layers, > > but I doubt you'll see them before mid-2.3. They're described in a paper > > at ftp://ftp.uk.linux.org/pub/linux/sct/fs/jfs/. > > > > Stephen - could some of the API be exported to userspace for use by things > > like databases which want similar transaction support? > >No, the requirements of filesystems are very specialised: in >particular you know you are only going to be dealing with small sets >of updates, and you have very relaxed locking requirements. >General-purpose application-level journaling is MUCH more complex --- >get a database, that's what they are there for. > >Note that libdb2 in glibc supports transactions, btw. > >--Stephen >
If copy-on-write was supported for files, you could use it for simple journaling - c-o-w copy the file, modify the new version, delete the old. This provides protection against application crash more than system crash though, I would imagine.
-----kbealier.at.stny.lrun.com------------------------------------- *Don't* background it, just sit there looking at it. Tell everyone "I'll get back to you as soon as this here job is finished". Very relaxing.
-- Lars P. Fischer
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