Re: Define conflict between ext3 and raid patches against 2.2.19

[Mike Fedyk <mfedyk@matchmail.com>]

On Fri, Sep 21, 2001 at 02:10:50PM +0100, Stephen C. Tweedie wrote:
> Hi,
> 
> On Thu, Sep 20, 2001 at 08:35:04AM +1000, Neil Brown wrote:
> 
> > However when a RAID rebuild happens, every block on the array is read
> > into the buffer cache (if it isn't already there) and then written
> > back out again.  This defeats the control that ext3 tries to maintain
> > on the buffer cache.
> > 
> > I don't know exactly what large-scale effects this might have.  It
> > could be simply that a crash at the wrong time could leave the
> > filesystem corrupted.
> 
> Immediately after a crash, the fs will be OK.  But during the
> subsequent background raid reconstruction, it can get out of sync
> again.  This can result in silent data loss in some cases, but it is
> also likely to trigger some internal ext3 debugging which detects
> out-of-order data writes, resulting in a kernel panic.
> 

Ok, thanks guys, on ext3-users and lkml.

Now I know that if I want RAID1 or RAID5 with ext3, I'm going to need 2.4...

Test test test...

Mike