From owner-freebsd-fs@FreeBSD.ORG Thu May 12 08:02:49 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 7EE7C106566C for ; Thu, 12 May 2011 08:02:49 +0000 (UTC) (envelope-from numisemis@gmail.com) Received: from mail-ww0-f50.google.com (mail-ww0-f50.google.com [74.125.82.50]) by mx1.freebsd.org (Postfix) with ESMTP id 0BE818FC16 for ; Thu, 12 May 2011 08:02:48 +0000 (UTC) Received: by wwc33 with SMTP id 33so1417854wwc.31 for ; Thu, 12 May 2011 01:02:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:content-type:mime-version:subject:from :in-reply-to:date:content-transfer-encoding:message-id:references:to :x-mailer; bh=y5Bfw6bWyC1G9CFze8Vs2J3W+YtO5U4YJGjskubuCFI=; b=r0CDomCnXi0ERwWbds0jmDZTh/iu6P44pXOg+ksMoM00g2Hf9iuSka/wS6qUCc+tl8 uMJUuhRC6gXakY0CDg00ij50LcvpTZs4ufuH3JG8nst5qbXA4xMSMNZygpwfBUY6drEp 4oM06UR09SABIxAgfcKodHottIfK6Uy8P+w9A= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=content-type:mime-version:subject:from:in-reply-to:date :content-transfer-encoding:message-id:references:to:x-mailer; b=R9OR9gWK+GkuAd4z0kFKi0R4Q89mcDk/klMt5QcK5y/3CoZDV6bt7m+GlfshxGeHOp 2FprGMBQ+hW9nqitMU70rWohNIbvWCYWO88wLRgO3Yu0OrEHULRUUF5w3cIuQgL8WFQc yFcmhELfq693JAPJfNDhUqsHRPcvamuE57BOQ= Received: by 10.216.79.11 with SMTP id h11mr4701200wee.77.1305187367760; Thu, 12 May 2011 01:02:47 -0700 (PDT) Received: from sime-imac.logos.hr ([213.147.110.159]) by mx.google.com with ESMTPS id t5sm473548wes.9.2011.05.12.01.02.46 (version=TLSv1/SSLv3 cipher=OTHER); Thu, 12 May 2011 01:02:46 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Apple Message framework v1084) From: =?iso-8859-2?Q?=A9imun_Mikecin?= In-Reply-To: <4DCB81B8.6070301@digsys.bg> Date: Thu, 12 May 2011 10:02:42 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: References: <4DCA5620.1030203@dannysplace.net> <4DCB455C.4020805@dannysplace.net> <4DCB81B8.6070301@digsys.bg> To: freebsd-fs X-Mailer: Apple Mail (2.1084) Subject: Re: ZFS: How to enable cache and logs. 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: Thu, 12 May 2011 08:02:49 -0000 On 12. svi. 2011., at 08:44, Daniel Kalchev wrote: > On 12.05.11 05:26, Danny Carroll wrote: >>=20 >> - Don't use SSD for the Log device. Write speed tends to be a = problem. > It all depends on your usage. You need to experiment, unfortunately. What is the alternative for log devices if you are not using SSD? Rotating hard drives? AFAIK, two factors define the speed of log device: write transfer rate = and write latency. You will not find a rotating hard drive that has a write latency = anything near the write latency of even a slowest SSD you can find on = the market. On the other hand, only a very few rotating hard drives have a write = transfer rate that can be compared to SSD's.