[linux-lvm] ReiserFS/XFS/JFS, LVM, Raid5
Stephen C. Tweedie
sct at redhat.com
Mon Jul 3 17:16:14 UTC 2000
Hi,
On Mon, Jul 03, 2000 at 06:16:27PM +0200, Andi Kleen wrote:
> On Mon, Jul 03, 2000 at 03:05:24PM +0100, Stephen C. Tweedie wrote:
> > The only known problem with journaling and software raid is to do with
> > the raid array rebuild code in raid1/5. The rebuild could cause I/O
> > to be done in the wrong order for the filesystem, causing clean blocks
> > in the buffer cache to be flushed to disk as part of the rebuild.
> > That is fixed in the 2.4 soft raid. raid0 and LVM were never affected
> > by this as they have no rebuild operation.
>
> Note this applies only to the RAID1 in Raid 0.90 or in 2.4.
> Unpatched 2.2 does Raid1 reconstruction in user space only and should be
> safe for journaling.
I think the user-space rebuild still has the same problem --- it
accesses the underlying raid device through the buffer cache, causing
clean buffers to be written to disk. That's enough to kill
journaling.
Cheers,
Stephen
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