> On Tue, 18 May 1999, Manfred Spraul wrote:
>
> >AFAIK, NTFS implements journaling with a logging fs:
> >they implemented 2 filesystems: the actual NTFS, and a logging fs
> >(called LFS) which is stored in a fixed size file on the volume.
> >I guess that the LFS is only written (and read during fsck).
>
> I guess the LFS is used _only_ for the metadata.
>
> >The wraparound is a huge problem: you might recall the one of the tweaks
> >which Mindcraft did on NT was:
> >'set the size of the log to a incredibly large number' (65 MB).
> >(the default should be somewhere around 4 MB, but the system gets
> >nearly stopped if the log overflows)
>
> For curiosity: do they defrag it while the system is idle? They should
> try in all ways to avoid the log to wrap. Otherwise they are forced to
> wait for I/O completation of the wrap-fault-handler.
>
> But the log-wrap is not the only problem, the other performance problem of
> a real logfs is that we are not going to always read _data_ (not only
> metadata) in the same order we write things to disk... And we are going to
> read _far_ more frequently than writes...
>
> Anyway a logfs still seems to me something of fun to play with ;).
Slashdot does have its uses... I read there just a couple of hours ago
that SGI has/intends to opensource XFS. That'd pretty much solve our need
for a fast Journaling filesystem, I think.
Comments?
/David Weinehall
_ _
// David Weinehall <tao@acc.umu.se> /> Northern lights wander \\
// Project MCA Linux hacker // Dance across the winter sky //
\> http://www.acc.umu.se/~tao/ </ Full colour fire </
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