Date: Sun, 17 Nov 2013 17:26:58 +0200 From: Vladimir Sharun <sharun@ukr.net> To: freebsd-fs@freebsd.org Subject: Re: ZFS: Memory needed for managing L2ARC Message-ID: <1384701881.854989070.jd2fimne@frv45.ukr.net> In-Reply-To: <alpine.BSF.2.00.1311171900130.8224@woozle.rinet.ru> References: <alpine.BSF.2.00.1311171900130.8224@woozle.rinet.ru>
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Depending on average block size cached. In my experience it varies from 0,3% to 5%. If you store lot of small files, consider 5-6%, mostly large files - 0,5%. Dear colleagues, are there any "real" estimations on how much memory is needed for having efficient, say, 1T of L2ARC? stable/amd64, of course. I have backup storage server, where pool size is targeted to a few hundreds of terabytes (currently ~35T), and hot set is usually less than 512G-1T. quick googling leads to some Solaris/Illumos documents, but even them are not bright enough in answer that. Thanks! -- Sincerely, D.Marck [DM5020, MCK-RIPE, DM3-RIPN] [ FreeBSD committer: marck@FreeBSD.org ] ------------------------------------------------------------------------ *** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck@rinet.ru *** ------------------------------------------------------------------------ _______________________________________________ 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" From owner-freebsd-fs@FreeBSD.ORG Sun Nov 17 15:28:41 2013 Return-Path: <owner-freebsd-fs@FreeBSD.ORG> Delivered-To: freebsd-fs@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id CEFB19DA for <freebsd-fs@FreeBSD.org>; Sun, 17 Nov 2013 15:28:41 +0000 (UTC) Received: from elsa.codelab.cz (elsa.codelab.cz [94.124.105.4]) (using TLSv1 with cipher ADH-CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 90741233D for <freebsd-fs@FreeBSD.org>; Sun, 17 Nov 2013 15:28:41 +0000 (UTC) Received: from elsa.codelab.cz (localhost [127.0.0.1]) by elsa.codelab.cz (Postfix) with ESMTP id 7FC722842E; Sun, 17 Nov 2013 16:28:33 +0100 (CET) Received: from [192.168.1.2] (ip-89-177-49-222.net.upcbroadband.cz [89.177.49.222]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by elsa.codelab.cz (Postfix) with ESMTPSA id 00CD32842B; Sun, 17 Nov 2013 16:28:30 +0100 (CET) Message-ID: <5288E09E.4010707@quip.cz> Date: Sun, 17 Nov 2013 16:28:30 +0100 From: Miroslav Lachman <000.fbsd@quip.cz> User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.9.1.19) Gecko/20110420 Lightning/1.0b1 SeaMonkey/2.0.14 MIME-Version: 1.0 To: Dmitry Morozovsky <marck@rinet.ru> Subject: Re: ZFS: Memory needed for managing L2ARC References: <alpine.BSF.2.00.1311171900130.8224@woozle.rinet.ru> In-Reply-To: <alpine.BSF.2.00.1311171900130.8224@woozle.rinet.ru> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-fs@FreeBSD.org X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.16 Precedence: list List-Id: Filesystems <freebsd-fs.freebsd.org> List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-fs>, <mailto:freebsd-fs-request@freebsd.org?subject=unsubscribe> List-Archive: <http://lists.freebsd.org/pipermail/freebsd-fs/>; List-Post: <mailto:freebsd-fs@freebsd.org> List-Help: <mailto:freebsd-fs-request@freebsd.org?subject=help> List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>, <mailto:freebsd-fs-request@freebsd.org?subject=subscribe> X-List-Received-Date: Sun, 17 Nov 2013 15:28:41 -0000 Dmitry Morozovsky wrote: > Dear colleagues, > > are there any "real" estimations on how much memory is needed for having > efficient, say, 1T of L2ARC? stable/amd64, of course. > > I have backup storage server, where pool size is targeted to a few hundreds of > terabytes (currently ~35T), and hot set is usually less than 512G-1T. > > quick googling leads to some Solaris/Illumos documents, but even them are not > bright enough in answer that. I have some old informations in a bookmarks: Re: [zfs-discuss] ZFS ZIL + L2ARC SSD Setup http://www.mail-archive.com/zfs-discuss@opensolaris.org/msg34674.html Approximately 200 bytes per record. I use the following example: Suppose we use a Seagate LP 2 TByte disk for the L2ARC + Disk has 3,907,029,168 512 byte sectors, guaranteed + Workload uses 8 kByte fixed record size RAM needed for arc_buf_hdr entries + Need = ~(3,907,029,168 - 9,232) * 200 / 16 = ~48 GBytes http://www.mail-archive.com/zfs-discuss@opensolaris.org/msg34677.html I hope this helps Miroslav Lachman
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