Re: Ext3 Filesystem

David Weinehall (tao@acc.umu.se)
Sat, 11 Dec 1999 21:26:21 +0100 (MET)


On 10 Dec 1999, Peter Samuelson wrote:

>
> [Dr. Michael Weller <eowmob@exp-math.uni-essen.de>]
> > I mean, what you really want is: have the journal on a separate
> > partition with no filesystem at all. Best of all on a seperate disk
> > (controller, maybe). And you might want to have one journal only for
> > all filesystems.
>
> AIX does this. There is one journal LV (logical volume) for each VG
> (volume group). This (rather than one journal per whole system) is
> because the VG is intended to be the unit of portability, i.e. you can
> eject a ZIP disk with a VG on it and the VG on it will work elsewhere.
> AIX's JFS is restricted to the LV/VG universe (it starts calling you
> nasty names if you try to create one on just any old block device), so
> this scheme works well.
>
> I don't think AIX makes any effort to load-balance the log between
> physical disks. It can't -- the size of the journal LV is the minimum.
>
> I agree that for load-balancing reasons it would be nice if ext3 moved
> in the direction of supporting journal-outside-fs and even a shared
> journal blockdev.

Well, considering that we have (or at least are going to have) an
LVM for Linux too, I believe we should do in the same manner IBM did with
AIX...

/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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