From owner-freebsd-fs@FreeBSD.ORG Fri Sep 17 16:46:06 2010 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 8240D1065670 for ; Fri, 17 Sep 2010 16:46:06 +0000 (UTC) (envelope-from bryan@shatow.net) Received: from secure.xzibition.com (secure.xzibition.com [173.160.118.92]) by mx1.freebsd.org (Postfix) with ESMTP id 2A3008FC25 for ; Fri, 17 Sep 2010 16:46:05 +0000 (UTC) DomainKey-Signature: a=rsa-sha1; c=nofws; d=shatow.net; h=message-id :date:from:mime-version:to:cc:subject:references:in-reply-to :content-type:content-transfer-encoding; q=dns; s=sweb; b=kgoQUL L23Liec7BLHfbddaqx7zHhJNQjeIHV/A74pZfq16QI5HDcOfPN26rxDee9jgLE0a Hd2EitfLHxNP8na2RJxwaZTFAKJnj8EQVIkjl5gYXcU5FwnEKDdNUvYGVCSXx4Ub 3/Ev2vhbXC68BH8XnqYJjfopm7nFcaAxfhxZo= DKIM-Signature: v=1; a=rsa-sha256; c=simple; d=shatow.net; h=message-id :date:from:mime-version:to:cc:subject:references:in-reply-to :content-type:content-transfer-encoding; s=sweb; bh=eANGZ+t8cp1j kUZTn27H5bs0wdvIkvglPAE84steywg=; b=iikKk/W3USMfhEAb7H/Ht5VP5mDa CnSIqQh8ND6fdrwbddh2/BPEOgDR9mxKBeadc0taW7g4DXx9cmz7cXKzl9sJnHmt gcu+meCRXmCLOJtgumowjeNv9nb66Q1Lvw3fsU9oSVxI7db/QvXcaQrL1svpYFjX iuKPUXVwnhbxTHg= Received: (qmail 12263 invoked from network); 17 Sep 2010 11:46:04 -0500 Received: from unknown (HELO ?192.168.0.201?) (bryan@shatow.net@74.94.87.209) by sweb.xzibition.com with ESMTPA; 17 Sep 2010 11:46:04 -0500 Message-ID: <4C939B47.6030701@shatow.net> Date: Fri, 17 Sep 2010 11:45:59 -0500 From: Bryan Drewery User-Agent: Thunderbird 2.0.0.24 (Windows/20100228) MIME-Version: 1.0 To: Jeremy Chadwick References: <4C9385B0.2080909@shatow.net> <20100917161847.GA58503@icarus.home.lan> <20100917163732.GA59537@icarus.home.lan> In-Reply-To: <20100917163732.GA59537@icarus.home.lan> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-fs@freebsd.org Subject: Re: what happens to pool if ZIL dies on ZFS v14 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: Fri, 17 Sep 2010 16:46:06 -0000 > I was under the impression ZFS still managed to utilise the ZIL when a > pool didn't have any "log" devices associated with it (possibly some > sort of statically-allocated amount of RAM?) > > You can search the FreeBSD lists for people continually advocating > vfs.zfs.zil_disable=1. There's even a couple blog posts from engineers > talking about how the only way to get their filers to behave decently > was to disable the ZIL[1][2][3]. In most (every?) cases I've seen where > someone advocates disabling the ZIL, pool details aren't provided, which > leads me to believe their pools have no "log" devices. > > Here's a better way to phrase my question: does vfs.zfs.zil_disable=1 do > anything if there aren't any "log" devices in use (in any pool)? > > > [1]: http://jmlittle.blogspot.com/2010/03/zfs-log-devices-review-of-ddrdrive-x1.html > [2]: http://blogs.sun.com/erickustarz/entry/zil_disable > [3]: http://weblog.etherized.com/posts/130 > > The ZIL is still used even without a dedicated log device. Disabling it is *stupid* in most cases. Same goes for disabling the ARC. There is a lot of FUD out there regarding ZFS tuning. The bottom line: don't tune; add more RAM. Bryan