From owner-freebsd-questions@FreeBSD.ORG Tue Sep 2 13:09:14 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 4484116A549; Tue, 2 Sep 2003 13:09:14 -0700 (PDT) Received: from Chow.corp.media.net (rottie.media.net [66.113.65.4]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1620B43FE5; Tue, 2 Sep 2003 13:09:13 -0700 (PDT) (envelope-from max.clark@media.net) Received: from MCLARK (76.0.6.10.IN-ADDR.ARPA [10.6.0.76]) by Chow.corp.media.net (Netscape Messaging Server 4.15) with SMTP id HKLRRG00.D3I; Tue, 2 Sep 2003 13:04:28 -0700 From: "Max Clark" To: "Poul-Henning Kamp" Date: Tue, 2 Sep 2003 13:14:58 -0700 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0) Importance: Normal In-Reply-To: <50599.1062532904@critter.freebsd.dk> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 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 20:09:14 -0000 I know adding ccd/vinum to the equation will lower my IO throughput, but the question is... if I have an external hardware shelf with 3.5TB (16 250GB drives w/ Raid 5 from hardware) and I put a Raid 0 stripe across 3 of these shelves what would my expected loss of IO be? Thanks, Max -----Original Message----- From: Poul-Henning Kamp [mailto:phk@phk.freebsd.dk] Sent: Tuesday, September 02, 2003 1:02 PM To: Max Clark Cc: freebsd-questions@freebsd.org; freebsd-performance@freebsd.org; freebsd-hackers@freebsd.org Subject: Re: FW: 20TB Storage System 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.