From owner-freebsd-fs@FreeBSD.ORG Tue Jul 10 19:31:10 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E1E731065670 for ; Tue, 10 Jul 2012 19:31:10 +0000 (UTC) (envelope-from rincebrain@gmail.com) Received: from mail-qc0-f182.google.com (mail-qc0-f182.google.com [209.85.216.182]) by mx1.freebsd.org (Postfix) with ESMTP id 960578FC0C for ; Tue, 10 Jul 2012 19:31:10 +0000 (UTC) Received: by qcsg15 with SMTP id g15so359030qcs.13 for ; Tue, 10 Jul 2012 12:31:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=efy/IfOav50Jvtke62aNcuLidAPjssQ/Hc4KQFLwCXk=; b=mw+y6QAl4NcCHSnw1M8qdMx+75R4l+tBLMAsQnUZZrJWHDkEC69Dk7VzT1xqisieFy sYhVMgIjJV49FbbIM8N5QPya8d7qyTTpdVA4eFp1qvetC3QwcfRyg5rWIY5gsD1MN+z0 sbPZIi3agCroPd/6F2eYeDrD1kemF0yXHv/W7OWrWF5lBZ8UwV39H5FFfT1mW38bD6oi aucTWMQ8Uh09A+bhM/DZTmE5ZfthOTJbf1d6c5L2hQoEkEtcok+mIJN8Qf5l6Ja8AOz3 JwQJAYSrMHSUc4Tem65aUGk6gwwaT9W661HqPXo4owvD2V/glYLG6NDutjg/r94V9u8w pXkQ== MIME-Version: 1.0 Received: by 10.224.117.13 with SMTP id o13mr82176221qaq.73.1341948669858; Tue, 10 Jul 2012 12:31:09 -0700 (PDT) Sender: rincebrain@gmail.com Received: by 10.229.40.4 with HTTP; Tue, 10 Jul 2012 12:31:09 -0700 (PDT) In-Reply-To: <1341946657.18535.YahooMailClassic@web122505.mail.ne1.yahoo.com> References: <1341946657.18535.YahooMailClassic@web122505.mail.ne1.yahoo.com> Date: Tue, 10 Jul 2012 15:31:09 -0400 X-Google-Sender-Auth: QRopeJgATBLnsXHZB97Tw4nmQq4 Message-ID: From: Rich To: Jason Usher Content-Type: text/plain; charset=UTF-8 Cc: freebsd-fs@freebsd.org Subject: Re: chaining JBOD chassic to server ... why am I scared ? (ZFS) X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 Jul 2012 19:31:11 -0000 There's not really a visible difference between either the head node or JBOD(s) losing power and e.g. a backplane failure - power lost, and then whatever happens depends on your disk configuration and distribution. The Supermicro chassis in question have the option to take 2.5 internal drives if desired, which is where I'd suggest root+(SLOG,L2ARC) [though the 36d ones don't, IIRC]. You may also get more mileage out of the 9207-8[ie] - not much cost difference, PCIe gen 3 and newer chip. [Can't speak to how it performs in practice other than that reviews seem to be positive; mine haven't arrived yet.] - Rich On Tue, Jul 10, 2012 at 2:57 PM, Jason Usher wrote: > The de-facto configuration the smart folks are using for ZFS seems to be: > > - 16/24/36 drive supermicro chassis > - LSI 9211-8i internal cards > - ZFS and probably raidz2 or raidz3 vdevs > > Ok, fine. But then I see some even smarter folks attaching the 48-drive 4U JBOD chassis to this configuration, probably using a different LSI card that has an external SAS cable. > > So ... 84 drives accessible to ZFS on one system. In terms of space and money efficiency, it sounds really great - fewer systems to manage, etc. > > But this scares me ... > > - two different power sources - so the "head unit" can lose power independent of the JBOD device ... how well does that turn out ? > > - external cabling - has anyone just yanked that external SAS cable a few times, and what does that look like ? > > - If you have a single SLOG, or a single L2ARC device, where do you put it ? And then what happens if "the other half" of the system detaches from the half that the SLOG/L2ARC is in ? > > - ... any number of other weird things ? > > > Just how well does ZFS v28 deal with these kind of situations, and do I have a good reason to be awfully shy about doing this ? > > > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org"