From owner-freebsd-stable@FreeBSD.ORG Fri Jan 7 01:28:12 2011 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1AC791065672 for ; Fri, 7 Jan 2011 01:28:12 +0000 (UTC) (envelope-from jyavenard@gmail.com) Received: from mail-iy0-f182.google.com (mail-iy0-f182.google.com [209.85.210.182]) by mx1.freebsd.org (Postfix) with ESMTP id D13438FC0A for ; Fri, 7 Jan 2011 01:28:11 +0000 (UTC) Received: by iyb26 with SMTP id 26so16056667iyb.13 for ; Thu, 06 Jan 2011 17:28:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:cc:content-type; bh=xfEZxhcQhA/8QI2RqEyumfcU42P8nNhrvbbfFN1lcoM=; b=nKC5wdH3Y4KebPziaTREzIBGAg4RnVdDvZuq0lshYEdQSy0HRddtjeyd8IzrI5zUCV SVTl1dMk9/FOERI8miN+tr8NV6PCdPa/bhTcTXXqxp3Sf3U/430NbZU1Gticbs6GURDO CJbygHjZUmnxtnhSdHM3KSwMRg0DhvuCGahQ0= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=oVLqJlzWhZIPVgShErk8oXQSdgTH27Mn1AhIzmP8Y5PB8449Yg4B6DdVkeVudZAtcB Wsv/bjEUQbLvVNBtWrW10srFr4r9rx1yLDldSH4Sm1tbSbOXP3/32Nic78A/p+eyLLqa J32sDAyNJeX4vvtj65rt7YXe3Ic1KEuM+v93k= MIME-Version: 1.0 Received: by 10.42.169.9 with SMTP id z9mr289017icy.89.1294363691199; Thu, 06 Jan 2011 17:28:11 -0800 (PST) Received: by 10.42.172.69 with HTTP; Thu, 6 Jan 2011 17:28:11 -0800 (PST) In-Reply-To: <4D25C760.4070703@digsys.bg> References: <4D1C6F90.3080206@my.gd> <4D21E679.80002@my.gd> <84882169-0461-480F-8B4C-58E794BCC8E6@my.gd> <488AE93A-97B9-4F01-AD0A-0098E4B329C3@my.gd> <4D25BF91.7070304@my.gd> <4D25C760.4070703@digsys.bg> Date: Fri, 7 Jan 2011 12:28:11 +1100 Message-ID: From: Jean-Yves Avenard To: Daniel Kalchev Content-Type: text/plain; charset=ISO-8859-1 Cc: freebsd-stable@freebsd.org Subject: Re: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 07 Jan 2011 01:28:12 -0000 Hi On 7 January 2011 00:45, Daniel Kalchev wrote: > For pure storage, that is a place you send/store files, you don't really > need the ZIL. You also need the L2ARC only if you read over and over again > the same dataset, which is larger than the available ARC (ZFS cache memory). > Both will not be significant for 'backup server' application, because it's > very unlikely to do lots of SYNC I/O (where separate ZIL helps), or serve > the same files back (where the L2ARC might help). > > You should also know that having large L2ARC requires that you also have > larger ARC, because there are data pointers in the ARC that point to the > L2ARC data. Someone will do good to the community to publish some reasonable > estimates of the memory needs, so that people do not end up with large but > unusable L2ARC setups. > > It seems that the upcoming v28 ZFS will help greatly with the ZIL in the > main pool.. yes, it made a *huge* difference for me.. It went from "way too slow to comprehend what's going on" to "still slow but I can live with it" and I found no significant difference between ZIL on the main pool and on a separate SSD