From owner-freebsd-scsi@freebsd.org Tue Feb 16 15:55:43 2016 Return-Path: Delivered-To: freebsd-scsi@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 287E9AA91FB for ; Tue, 16 Feb 2016 15:55:43 +0000 (UTC) (envelope-from asomers@gmail.com) Received: from mail-ob0-x22b.google.com (mail-ob0-x22b.google.com [IPv6:2607:f8b0:4003:c01::22b]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id DF3CE1C68 for ; Tue, 16 Feb 2016 15:55:42 +0000 (UTC) (envelope-from asomers@gmail.com) Received: by mail-ob0-x22b.google.com with SMTP id gc3so163254183obb.3 for ; Tue, 16 Feb 2016 07:55:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=uMJLk5Ncux4AGarFShHIEtX3DpOLhbW+7kabYd/uhMI=; b=ysUgpycxlp1U1BG3pGAoaqdBnmnJ1mNbXI/W9J8U+ptvrJy5M3hF5ssZFOhrwXnxxv hZ2NLEdumOjq2eyMEUeRS9FUgJZa1ofh1ixlMMudhGINRNyf2Xb4sEbWEvbYK27Ur6qD W86ojseC/fEqzCsUSoTKmjE7PRK00RQirNC42bVok27lHf8PFWI3YzKE5jYtU2eGic9f vUT2e7i4s48kMX39Zch+m3FL+BXqkXYt4JKJrAd/mtaP/vZkPN81fO5+EKH680RSvraR C0QybLOdVQ8Nt0Lu3SdYO22i/3UgwdOBEreNaEeG3mbskvcae2Dp25d5FBiVYafNaYIJ SjWQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:sender:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=uMJLk5Ncux4AGarFShHIEtX3DpOLhbW+7kabYd/uhMI=; b=Mt9YsDRHj/TIG5W3VtMx5vtIMqD1gZla2n/tvm98krhAAIOlF426Lo/FhRwSrDuAnK atllWGPqGt6latdmIAh70UjsZI1uWkeinn3D7t6UTHH4fsam25cg5tHDmCk1YJKNT1bb LRNTvUGsib/uqqJFU3ZzfF1kh6+8/qDQKM42+MHI5v0nc4UmoPSlyJci5/4cshxfcDqd QidNBCwVi0d+1hqWeyCYtRtCyFd/Lcad8yY3IIXB311HoFMvckp8swShvoP7MKDAfQge VSDkhEYkxIKazoZ9dIUzxhXCXkzLMVPsJYfDlTZs0NK4jg/Y675hu+mkn20sXNbh5wjY s8jw== X-Gm-Message-State: AG10YOTonZsnbvtJ5bGEgB8xtZmuPrg5vjnZsfLcxlqxjQeRPrvB7f/RqZToovONUFgix/BruVdvGRz7z3Dp1A== MIME-Version: 1.0 X-Received: by 10.60.246.74 with SMTP id xu10mr17349068oec.31.1455638135303; Tue, 16 Feb 2016 07:55:35 -0800 (PST) Sender: asomers@gmail.com Received: by 10.202.78.83 with HTTP; Tue, 16 Feb 2016 07:55:35 -0800 (PST) In-Reply-To: References: Date: Tue, 16 Feb 2016 08:55:35 -0700 X-Google-Sender-Auth: jk2mj6cN8vsT3_mehyyS69roVUU Message-ID: Subject: Re: camcontrol sata affiliations From: Alan Somers To: David Ford Cc: "freebsd-scsi@freebsd.org" Content-Type: text/plain; charset=UTF-8 X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 16 Feb 2016 15:55:43 -0000 On Tue, Feb 16, 2016 at 8:32 AM, David Ford wrote: >> -----Original Message----- >> From: asomers@gmail.com [mailto:asomers@gmail.com] On Behalf Of Alan Somers >> Sent: 16 February 2016 15:23 >> To: David Ford >> Cc: freebsd-scsi@freebsd.org >> Subject: Re: camcontrol sata affiliations >> >> You aren't missing anything. This is just a difference between SATA >> and SAS. SAS drives have two ports, and SATA drives have only one. >> Most (all?) multipath JBODs like yours have two separate expander >> chips. They connect every slot's first port to the first expander and >> every slot's second port to the second expander. That results in a >> chassis with no SPOF. With such hardware, there's no way to connect a >> SATA drive to both servers. And with more complicated hardware that >> uses a single expander chip combined with SAS zoning to connect a SATA >> drive to two servers, you're stuck with a SPOF. > > Thanks that at least clarifies what's going on. I had understood most of that, > however I thought that the idea of the ability to clear the affiliation > was to permit the second expander to take over. I suspect I was mistaken. > > Thanks > > David > Only if you have a JBOD that uses a single expander chip for both hosts. Then I think those commands would do what you want.