From owner-freebsd-fs@FreeBSD.ORG Sun Oct 16 16:17:51 2011 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 E42491065672 for ; Sun, 16 Oct 2011 16:17:51 +0000 (UTC) (envelope-from daniel@digsys.bg) Received: from smtp-sofia.digsys.bg (smtp-sofia.digsys.bg [193.68.3.230]) by mx1.freebsd.org (Postfix) with ESMTP id 6DB5A8FC16 for ; Sun, 16 Oct 2011 16:17:50 +0000 (UTC) Received: from [192.92.129.101] ([192.92.129.101]) (authenticated bits=0) by smtp-sofia.digsys.bg (8.14.4/8.14.4) with ESMTP id p9GGHcTa026595 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Sun, 16 Oct 2011 19:17:44 +0300 (EEST) (envelope-from daniel@digsys.bg) Mime-Version: 1.0 (Apple Message framework v1251.1) Content-Type: text/plain; charset=us-ascii From: Daniel Kalchev In-Reply-To: <4E9AE725.4040001@gmail.com> Date: Sun, 16 Oct 2011 19:17:39 +0300 Content-Transfer-Encoding: quoted-printable Message-Id: <169E82FD-3B61-4CAB-B067-D380D69CDED5@digsys.bg> References: <4E9AE725.4040001@gmail.com> To: "Luchesar V. ILIEV" X-Mailer: Apple Mail (2.1251.1) Cc: freebsd-fs@freebsd.org Subject: Re: [ZFS] Using SSD with partitions 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: Sun, 16 Oct 2011 16:17:52 -0000 On Oct 16, 2011, at 17:16 , Luchesar V. ILIEV wrote: > 6. If, OTOH, you're running a reasonably recent -STABLE (8 or 9), then > your zpool version is likely 28 (thanks, pjd@), which means ZIL is not > that scary, but you might still lose some data. Even an unexpected = power > failure might cause trouble, unless the SSD is designed to handle it > gracefully (this typically involves some sort of capacitor). Just for the record: even without ZIL, you will most definitely lose = data at power outage. In most cases, this will not damage the ZFS = filesystem, but data will be lost. There is nothing that can prevent = this. Therefore, with ZFS v28, adding ZIL does not introduce any more risk to = your data. One thing to have in mind is ZIL will help only under certain workloads, = sequential write is not one of these. It helps most with database-type = loads and sync writes like an NFS server that is written heavily. = Freddie have good advice on determining if it will help. L2ARC on the other hand may help enormously, especially if the spool is = big. Workstation-class motherboards until recently were topped at 8GB = RAM and ZFS is happy with as much RAM as you can offer. Adding L2ARC may = provide more headroom. Benefits of course depend on the workload. = Neither L2ARC or ZIL provide magical benefits. Daniel=