From owner-freebsd-current Mon Mar 17 22:53:46 2003 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 07A2137B404; Mon, 17 Mar 2003 22:53:44 -0800 (PST) Received: from wantadilla.lemis.com (wantadilla.lemis.com [192.109.197.80]) by mx1.FreeBSD.org (Postfix) with ESMTP id 735C243F85; Mon, 17 Mar 2003 22:53:41 -0800 (PST) (envelope-from grog@lemis.com) Received: by wantadilla.lemis.com (Postfix, from userid 1004) id 6002851A62; Tue, 18 Mar 2003 17:23:39 +1030 (CST) Date: Tue, 18 Mar 2003 17:23:39 +1030 From: Greg 'groggy' Lehey To: Jeff Roberson Cc: Terry Lambert , Brooks Davis , Julian Elischer , Alfred Perlstein , FreeBSD current users , fs@FreeBSD.ORG Subject: Software RAID caching? (was: Anyone working on fsck?) Message-ID: <20030318065339.GQ84879@wantadilla.lemis.com> References: <3E769970.3A05ECAF@mindspring.com> <20030317230147.I66343-100000@mail.chesapeake.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="uRjmd8ppyyws0Tml" Content-Disposition: inline In-Reply-To: <20030317230147.I66343-100000@mail.chesapeake.net> User-Agent: Mutt/1.4i Organization: The FreeBSD Project Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-418-838-708 WWW-Home-Page: http://www.FreeBSD.org/ X-PGP-Fingerprint: 9A1B 8202 BCCE B846 F92F 09AC 22E6 F290 507A 4223 Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG --uRjmd8ppyyws0Tml Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Monday, 17 March 2003 at 23:02:38 -0500, Jeff Roberson wrote: > On Mon, 17 Mar 2003, Terry Lambert wrote: > >> Jeff Roberson wrote: >>> On Mon, 17 Mar 2003, Brooks Davis wrote: >>>> I am still intrested in improvements to fsck since I'm planning to buy >>>> several systems with two 1.4TB IDE RAID5 arrays in them soon. >>> >>> For these types of systems doing a block caching layer with a prefetch >>> that understands how many spindles there are would be a huge benefit. >> >> I call that layer "Vinum" or "RAIDFrame", since that's a job I >> expect that code to do for me. 8-). > > They are not responsible for data caching. Only informing the upper > layers how many spindles they have. Software RAID should be a transform > only in my opinion. There is no reason to have duplicate block caches in > system memory. Agreed. Vinum doesn't cache. There is one case, though, where it could be argued that it's worthwhile, namely in RAID-[45] parity blocks. Greg -- See complete headers for address and phone numbers --uRjmd8ppyyws0Tml Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.0 (FreeBSD) iD8DBQE+dsJzIubykFB6QiMRAnxRAKCchEJe3ef58LaGhKV3ryDQ2KWSuwCffM0d IDGm/1c4dUXxIubQoi4Uq90= =TNJT -----END PGP SIGNATURE----- --uRjmd8ppyyws0Tml-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message