From owner-freebsd-geom@FreeBSD.ORG Sat Sep 25 14:52:38 2004 Return-Path: Delivered-To: freebsd-geom@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8F09416A4CE for ; Sat, 25 Sep 2004 14:52:38 +0000 (GMT) Received: from darkness.comp.waw.pl (darkness.comp.waw.pl [195.117.238.136]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2003B43D55 for ; Sat, 25 Sep 2004 14:52:38 +0000 (GMT) (envelope-from pjd@darkness.comp.waw.pl) Received: by darkness.comp.waw.pl (Postfix, from userid 1009) id 3B09BACAFE; Sat, 25 Sep 2004 16:52:36 +0200 (CEST) Date: Sat, 25 Sep 2004 16:52:36 +0200 From: Pawel Jakub Dawidek To: Paul Mather Message-ID: <20040925145236.GO9550@darkness.comp.waw.pl> References: <1095993821.5665.124.camel@zappa.Chelsea-Ct.Org> <20040924075553.GE9550@darkness.comp.waw.pl> <1096062713.9306.119.camel@zappa.Chelsea-Ct.Org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="TRkqPRiqIDKgfg/F" Content-Disposition: inline In-Reply-To: <1096062713.9306.119.camel@zappa.Chelsea-Ct.Org> User-Agent: Mutt/1.4.2i X-PGP-Key-URL: http://people.freebsd.org/~pjd/pjd.asc X-OS: FreeBSD 5.2.1-RC2 i386 cc: freebsd-geom@freebsd.org Subject: Re: gstripe stripe size units? X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 25 Sep 2004 14:52:38 -0000 --TRkqPRiqIDKgfg/F Content-Type: text/plain; charset=iso-8859-2 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Sep 24, 2004 at 05:51:54PM -0400, Paul Mather wrote: +> > If gstripe is running in "fast" mode (kern.geom.stripe.fast=3D1), size= of +> > stripe could be small, because then, it still sends as large I/O reque= sts +> > as possible and reorganize the data in memory, but this method consumes +> > a lot of memory if you want it to be efficient. +>=20 +> One thing that puzzles me is that no matter how large I made the stripe +> size, I never got a kern.geom.stripe.fast_failed > 0. [...] It will be hard for raidtest tests, but it is really easy for UFS+softupdates and small stripe size. +> I'm puzzled because a stripe of 16 MB will not fit in 6553600 bytes, so +> surely fast_failed should be > 0 at stripes of 8 MB or greater in my +> tests for the above value of kern.geom.stripe.maxmem? This is a problem for small stripe sizes, not for big ones. Remember, that no metter how large stripe size is, maximum I/O request size is still 128kB, so for stripe size >=3D 64kB there is not even chance to fail - gstripe don't allocate memory if it is not needed, i.e. if we can split request on two pieces or even send it as one piece. +> Also, I don't know what the distribution of request sizes is in +> raidtest.data. The raidtest program operates over the raw device, and +> so may not necessarily behave in terms of issuing requests as, say, a +> UFS filesystem might. Of course. You should run some file systems tests as well. --=20 Pawel Jakub Dawidek http://www.FreeBSD.org pjd@FreeBSD.org http://garage.freebsd.pl FreeBSD committer Am I Evil? Yes, I Am! --TRkqPRiqIDKgfg/F Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (FreeBSD) iD8DBQFBVYY0ForvXbEpPzQRAqYcAJ9e5LXWgcpMI+P4usPwszlcfks7AwCeKehD PslUqk8dcrJ2ggUFGQNh6yE= =QiNi -----END PGP SIGNATURE----- --TRkqPRiqIDKgfg/F--