From owner-freebsd-hackers@FreeBSD.ORG Sun Nov 16 00:35:48 2014 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 4E646470 for ; Sun, 16 Nov 2014 00:35:48 +0000 (UTC) Received: from mail-qg0-f43.google.com (mail-qg0-f43.google.com [209.85.192.43]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 10DE5C47 for ; Sun, 16 Nov 2014 00:35:47 +0000 (UTC) Received: by mail-qg0-f43.google.com with SMTP id f51so13936085qge.30 for ; Sat, 15 Nov 2014 16:35:41 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type; bh=9oQlPhRg3U2mJh/0WgoHVQnbyYh7LF81Dri5NQJ1WGQ=; b=kyV5/UjC5T23zzutTDf+co+7YualObkrzCdkrsaD28XniDpTw0IrgKGb8A0Y0Oe2yW NiMj0GnHXQR6+DtOvVYLj74XL7RcxhLRmCS5zaNfX1te0jp5VtEqiuRfIJsDiYz/ypnC IiNRAN0EblDHZo5UJ0vTEwgBGcAXngZ1UhHj7dDoRaSEznZdaQLdpoueYwkdftKLZr9Z lp2xp57/q4svpq9sYO6mifYfWmU0HLSuh112FL+TSvq6VAjCwXIbzkCufqRo6fCDkCwa 5DUQdIX1V9Ks8B2E/6LdGOeaB4CKsknJoC0qWkfVPer5zx01DxyoTMuhI322UfmvYQ5x 8XIA== X-Gm-Message-State: ALoCoQk6dcSM0xcW0Xzrk43Us8Mhy1Z8pG3Od3zSIsZNEzhdwJ2/laqEQvQNltGR2aFBIo3Evwix MIME-Version: 1.0 X-Received: by 10.224.131.135 with SMTP id x7mr22978565qas.38.1416098140943; Sat, 15 Nov 2014 16:35:40 -0800 (PST) Received: by 10.140.95.193 with HTTP; Sat, 15 Nov 2014 16:35:40 -0800 (PST) In-Reply-To: References: Date: Sat, 15 Nov 2014 17:35:40 -0700 Message-ID: Subject: Re: OT-ish SATA port replicators vs. SAS "expanders" From: Brandon Vincent To: FreeBSD Hackers Content-Type: text/plain; charset=UTF-8 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 16 Nov 2014 00:35:48 -0000 On Sat, Nov 15, 2014 at 3:42 PM, Zaphod Beeblebrox wrote: > What is the real difference? Is it possible to hack the driver to support > (obviously not booting from) SATA port replicators on the LSI? This website has a lot of good information on the benefits of using SAS expanders versus SATA port replicators [1]. Most of the storage requirements demanded by large enterprise organizations can only be met using SAS expanders (e.g. multipath I/O). You should also consider that while SATA port replicators work, they are not as nearly as reliable as SAS expanders [2]. SAS is typically utilized for high performance storage applications that have a high reliability requirement. In the end, your choice of solution depends on your application. Are you working in a data warehouse with a five nines availability requirement or are you experimenting at home? For the later, SATA is the economical choice, while SATA doesn't quite cut it for the enterprise requirement. Where did you find that the LSI chipset doesn't support SATA port replicators? Brandon Vincent [1] http://www.sasexpanders.com [2] https://www.usenix.org/system/files/fastpw13-paper7_0.pdf