From owner-freebsd-hardware@freebsd.org Tue Nov 7 08:42:51 2017 Return-Path: Delivered-To: freebsd-hardware@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 4AB59E52A30 for ; Tue, 7 Nov 2017 08:42:51 +0000 (UTC) (envelope-from frank2@fjl.co.uk) Received: from bs1.fjl.org.uk (bs1.fjl.org.uk [84.45.41.196]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "bs1.fjl.org.uk", Issuer "bs1.fjl.org.uk" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id E12AB6FCDD for ; Tue, 7 Nov 2017 08:42:50 +0000 (UTC) (envelope-from frank2@fjl.co.uk) Received: from [192.168.1.162] (host81-134-87-65.range81-130.btcentralplus.com [81.134.87.65]) (authenticated bits=0) by bs1.fjl.org.uk (8.14.4/8.14.4) with ESMTP id vA78eEGn058827 (version=TLSv1/SSLv3 cipher=DHE-DSS-AES128-SHA bits=128 verify=NO) for ; Tue, 7 Nov 2017 08:40:22 GMT (envelope-from frank2@fjl.co.uk) Message-ID: <5A00C4D5.2010205@fjl.co.uk> Date: Mon, 06 Nov 2017 20:23:49 +0000 From: Frank Leonhardt Reply-To: frank2@fjl.co.uk Organization: Frank Leonhardt User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: freebsd-hardware@freebsd.org Subject: Re: Do I need SAS drives?.. References: <4DFBCE11-913A-4FC9-937D-463B4D49816C@aldan.algebra.com> In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.23 X-BeenThere: freebsd-hardware@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 07 Nov 2017 08:42:51 -0000 On 06/11/2017 10:09, Zane C. B-H. wrote: > In my years of doing decade plus of DC work, I've seen both SAS and SATA > drives flake and render systems in operable till the offending drive is > removed. > My experience too. > For Supermicro it will vary between backplanes. > Very true indeed. If they go on or off from time to time, that's good enough. >> I'm guessing that you don't have an expander (since you only have 8 >> slots), so item 1 doesn't matter to you. I'll guess that item 3 >> doesn't matter either, or you wouldn't have asked this question. Item >> 5 can be dealt with simply by buying the higher end SATA drives. So >> item 6 is really the most important. If this system needs to have >> very high uptime and consistent bandwidth, or if it will be difficult >> to access for maintenance, then you probably want to use SAS drives. >> If not, then you can save some money by using SATA. Hope that helps. > > Actually most boxes with more than 4 slots tend to be use multipliers. > I'm more mixed on that. There are quite a few Dells with eight or twelve-slot backplanes, even if it means two HBAs. Apart from better performance, the cost of 2xHBA+backplane is bizarrely less than 1xHBA+Expander. All the Supermicros I've seen have had expanders though. > As to uptime, that is trivial to achieve with both. > > With both it is of importance of drive monitoring and regular self tests. WHS! Biggest cause of problems is discovering a flaky drive or two AFTER the redundant one has failed. I don't know what anyone else thinks, but I'm inclined to do a straightforward read of a block device rather than a ZFS scrub because (a) I think it's quicker, especially when there's not much workload; and (b) it also reads unused blocks, which are probably the majority. "Best Practice" says you should do a scrub every three months - seems way to long a gap for my liking.