From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 3 Jul 2000 18:16:14 +0100 From: "Stephen C. Tweedie" Subject: Re: [linux-lvm] ReiserFS/XFS/JFS, LVM, Raid5 Message-ID: <20000703181614.N3284@redhat.com> References: <20000703150524.E2931@redhat.com> <20000703181627.A19757@gruyere.muc.suse.de> Mime-Version: 1.0 Content-Disposition: inline In-Reply-To: <20000703181627.A19757@gruyere.muc.suse.de>; from ak@suse.de on Mon, Jul 03, 2000 at 06:16:27PM +0200 Sender: owner-linux-lvm Errors-To: owner-linux-lvm List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andi Kleen Cc: "Stephen C. Tweedie" , Jean-Eric Cuendet , linux-lvm@msede.com 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