From owner-freebsd-current@FreeBSD.ORG Tue Mar 21 18:41:29 2006 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0300816A41F; Tue, 21 Mar 2006 18:41:29 +0000 (UTC) (envelope-from kris@obsecurity.org) Received: from elvis.mu.org (elvis.mu.org [192.203.228.196]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7042543D49; Tue, 21 Mar 2006 18:41:28 +0000 (GMT) (envelope-from kris@obsecurity.org) Received: from obsecurity.dyndns.org (elvis.mu.org [192.203.228.196]) by elvis.mu.org (Postfix) with ESMTP id 5960F1A4DCD; Tue, 21 Mar 2006 10:41:28 -0800 (PST) Received: by obsecurity.dyndns.org (Postfix, from userid 1000) id BF7F651FCA; Tue, 21 Mar 2006 13:41:27 -0500 (EST) Date: Tue, 21 Mar 2006 13:41:27 -0500 From: Kris Kennaway To: John Kozubik Message-ID: <20060321184127.GA19204@xor.obsecurity.org> References: <20060320224313.O55763@kozubik.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="J2SCkAp4GZ/dPZZf" Content-Disposition: inline In-Reply-To: <20060320224313.O55763@kozubik.com> User-Agent: Mutt/1.4.2.1i Cc: freebsd-fs@freebsd.org, jroberson@chesapeake.net, freebsd-current@freebsd.org, tegge@freebsd.org, kris@obsecurity.org Subject: Re: UFS2 Snapshots in 6.1-Beta4 - Confirmed Problems X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Mar 2006 18:41:29 -0000 --J2SCkAp4GZ/dPZZf Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Mar 21, 2006 at 01:36:44AM -0800, John Kozubik wrote: > Here is the behavior I have witnessed: >=20 >=20 > First, I have confirmed that a filesystem with multiple snapshots that > undergoes multiple, rapid deletions of files, will cause the system to > hang. I have witnessed this before, but had not confirmed it or > documented it in a PR. Now that I have confirmed this behavior, I have > documented it in: kern/94769 >=20 > This is a serious problem because, in addition to making it nearly > impossible to run a system with multiple snapshots, it is conceivable that > enough rapid file deletions could occur on an otherwise non snapshotted > system that has a single snapshot on it due to a background fsck, to cause > the system to hang. > Second, kern/92292 is still a problem. I have reproduced this error in > 6.1-BETA4 (and have seen it happening since 5.1). The (small) difference > is that the cp process seems to stick in the flswai state instead of > biowr. Thanks, I'll try to reproduce these two. > This next one is complicated, and I haven't submitted a PR for it yet, but > I believe it is quite serious for reasons I will expand on below. >=20 > The problem is: If you completely fill a filesystem (109% usage in `df` > on most systems) that has a snapshot on it, the system becomes very > unresponsive - all interactive and disk response lags terribly and, > although the system is not hung, it is in many cases unusable. Yes :-( This will probably not be fixable in time for 6.1, but hopefully it will be addressed in the future. FYI, the system may also panic in this situation. Kris --J2SCkAp4GZ/dPZZf Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.2 (FreeBSD) iD8DBQFEIEjWWry0BWjoQKURAhsiAJ9hM3S6oc9mSZmlT+/ArqJIrv8oGgCgsDkQ 5Vh0MycEjF/FC8O7VT9IXL8= =RopU -----END PGP SIGNATURE----- --J2SCkAp4GZ/dPZZf--