From owner-freebsd-questions@freebsd.org Wed Feb 17 20:27:10 2016 Return-Path: Delivered-To: freebsd-questions@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 12D84AAAB43 for ; Wed, 17 Feb 2016 20:27:10 +0000 (UTC) (envelope-from merlyn@geeks.org) Received: from mail.geeks.org (jacobs.geeks.org [204.153.247.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id EB19215E3 for ; Wed, 17 Feb 2016 20:27:09 +0000 (UTC) (envelope-from merlyn@geeks.org) Received: from mail.geeks.org (localhost [127.0.0.1]) by after-clamsmtpd.geeks.org (Postfix) with ESMTP id 88CD711020B; Wed, 17 Feb 2016 14:18:16 -0600 (CST) Received: by mail.geeks.org (Postfix, from userid 1003) id 626B011020A; Wed, 17 Feb 2016 14:18:16 -0600 (CST) Date: Wed, 17 Feb 2016 14:18:16 -0600 From: Doug McIntyre To: David Ford Cc: "'freebsd-questions@freebsd.org'" Subject: Re: multi-homed drive SATA drive affiliations Message-ID: <20160217201816.GA50395@geeks.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Virus-Scanned: ClamAV using ClamSMTP X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 17 Feb 2016 20:27:10 -0000 On Thu, Feb 11, 2016 at 03:23:31PM +0000, David Ford wrote: > I suspect I'm missing something obvious here, but I can't quite think what. I have a set of SAS disk shelves which are each dual homed to a pair of FreeBSD 10.1 systems... > The problem is that for SATA drives (the idea is the use SSDs for L2ARC/ZIL) SATA affiliations don't appear to be having the desired effect, the disks get assigned to one host when they are attached.. .. Are you using SAS Interposer boards on each of the SATA drives, or are they plugged directly into the SAS backplane? The only way SAS dual channel works is the SAS disks have additional pins on the connector, so they can talk out either port, while SATA disks only have one set of pins/port out to talk. Typically, a disk vendor if using SATA drives or other single-port limited hardware would install a SAS Interposer board on the backside of the SATA disk, so that it can talk dual port out to the SAS backplane. Ie. on Dell systems, they have disk trays with screw mounts that are labelled SAS (which butt the drive right up to the connector), or are labelled SATA, where it leaves room to mount a SAS interposer board, such as http://www.ebay.com/itm/USED-DELL-SATA-to-SAS-CN-0PN939-13740P15945-06-A-Server-Interposer-Board-/311518244215?hash=item4887ef2d77:g:6NkAAOSwAYtWKEwX on the backside of the tray. I've also seen trays like this on all the major storage vendors, but not so much any longer, since SAS SSD's are somewhat afordable now-a-days.