From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: Re: reiser4 plugins Date: Mon, 27 Jun 2005 16:28:41 -0400 Message-ID: <20050627202841.GA27805@thunk.org> References: <42BB7B32.4010100@slaphack.com> <200506240334.j5O3YowB008100@laptop11.inf.utfsm.cl> <20050627092138.GD11013@nysv.org> <20050627124255.GB6280@thunk.org> <42C0578F.7030608@namesys.com> <42C05F16.5000804@xfs.org> Mime-Version: 1.0 Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com Content-Disposition: inline In-Reply-To: <42C05F16.5000804@xfs.org> List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Steve Lord Cc: Hans Reiser , Markus T?rnqvist , Horst von Brand , David Masover , Alan Cox , Jeff Garzik , Christoph Hellwig , Andrew Morton , Linux Kernel Mailing List , ReiserFS List On Mon, Jun 27, 2005 at 03:18:30PM -0500, Steve Lord wrote: > I presume Ted is referring to problems guaranteeing the integrity of > the journal at recovery time. I am coming into this without all the > available context, so I may be barking up the wrong tree.... In > particular, I am not sure how journaling whole blocks protects > you from this. Actually, I was talking about the problem what happens when power fails while DMA'ing to the disk, and memory, which is more sensitive to voltage drops than the rest of the system, starts sending garbage to the bus, which the disk then faithfully writes to the inode table. As I recall, you were the one who told me about this problem, and how it was fixed in Irix by using a powerfail interrupt to abort DMA transfers, as well as giving me a program which tests for this condition (basically it writes known test pattern to the disk, and then you do an unclean shutdown, and you look to see if garbage is written to the disk instead of one of the known test patterns). If it wasn't you, it must have been Jim Mostek --- but I could have sworn it was you..... - Ted