From owner-freebsd-questions@FreeBSD.ORG Tue Sep 2 13:01:49 2003 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A047B16A4BF; Tue, 2 Sep 2003 13:01:49 -0700 (PDT) Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.86.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id 60EF044001; Tue, 2 Sep 2003 13:01:48 -0700 (PDT) (envelope-from phk@phk.freebsd.dk) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.12.9/8.12.9) with ESMTP id h82K1ii8050600; Tue, 2 Sep 2003 22:01:45 +0200 (CEST) (envelope-from phk@phk.freebsd.dk) To: "Max Clark" From: "Poul-Henning Kamp" In-Reply-To: Your message of "Tue, 02 Sep 2003 12:48:29 PDT." Date: Tue, 02 Sep 2003 22:01:44 +0200 Message-ID: <50599.1062532904@critter.freebsd.dk> cc: freebsd-hackers@freebsd.org cc: freebsd-performance@freebsd.org cc: freebsd-questions@freebsd.org Subject: Re: FW: 20TB Storage System X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 02 Sep 2003 20:01:49 -0000 In message , "Max Clark" writ es: >Given the above: >1) What would my expected IO be using vinum to stripe the storage enclosures >detailed above? That depends a lot on the applications I/O pattern, an I doubt a precise prediction is possible. In particular the FibreChannel is hard to predict the throughput off because the various implementations seems to have each their own peculiar quirks performance wise. On a SEAGATE ST318452 disks, I see sequential transfer rates at the outside rim of the disk of 58MB/sec. If I stripe two of them them with CCD I get 107MB/sec. CCD has a better performance than Vinum where they compare. RAID-5 and striping a large number of disks does not scale linearly performance wise, in particular you _may_ see your average access time drop somewhat, but there is by far no guarantee that it will be better than the individual drive. >2) What is the maximum size of a filesystem that I can present to the host >OS using vinum/ccd? Am I limited anywhere that I am not aware of? Good question, I'm not sure we currently know the exact barrier. >3) Could I put all 20TB on one system, or will I need two to sustain the IO >required? Spreading it will give you more I/O bandwidth. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.