From owner-freebsd-fs@FreeBSD.ORG Fri Oct 24 06:52:36 2014 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 1591DE89 for ; Fri, 24 Oct 2014 06:52:36 +0000 (UTC) Received: from mail-yh0-x236.google.com (mail-yh0-x236.google.com [IPv6:2607:f8b0:4002:c01::236]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id CBD18FEB for ; Fri, 24 Oct 2014 06:52:35 +0000 (UTC) Received: by mail-yh0-f54.google.com with SMTP id 29so3358461yhl.41 for ; Thu, 23 Oct 2014 23:52:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=u+5o/vu+M7yjWTtzVKA4rbhniN8EohuphovD6OXDF5Y=; b=ObyVR9OUdyiOaxODAsWSmZ7nP3WjBn3z4hmg/UyGaSWotJdtwtc7RYGjMW4O5hxG+M loBuDOvFxxXH+vbj0cggFbKAjstyJFWuaYW3GLKqNLwqCCwPmI8PknrE079Tgvofsz7J Z7Ea3mPPzlJIYaGW0DugVJSJZ3l+7/6gdfo/2a04ufQcfm14iY874Oypn61Y3kTaJCj9 pMjydGNx2MGrC9JN492PfvxZRXtoa15weo2fP4M+jJHLdTawu8gPG95PYca52wkuMvQn gZzhlfNeID5MRbt5VxThvVVzZpXk2mPuX4JD+IGY4nBK/2aqk8kdiDCOVPAJutFKzJMM 1wdA== MIME-Version: 1.0 X-Received: by 10.170.197.150 with SMTP id o144mr3302802yke.103.1414133554051; Thu, 23 Oct 2014 23:52:34 -0700 (PDT) Received: by 10.170.156.139 with HTTP; Thu, 23 Oct 2014 23:52:34 -0700 (PDT) In-Reply-To: <5F9E965F5A80BC468BE5F40576769F099DF6E88A@exchange2-1> References: <5F9E965F5A80BC468BE5F40576769F099DF6E88A@exchange2-1> Date: Fri, 24 Oct 2014 07:52:34 +0100 Message-ID: Subject: Re: How big can ZFS L2ARC grow? From: krad To: =?UTF-8?Q?Karli_Sj=C3=B6berg?= Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.18-1 Cc: "freebsd-fs@freebsd.org" X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 24 Oct 2014 06:52:36 -0000 doesn l2arc have compression these days? On 23 October 2014 14:29, Karli Sj=C3=B6berg wrote: > Hey! > > As the topic states, I=C2=B4m wondering about the size of L2ARC and if th= ere > is a limit to how big it is able to grow. > > Why I=C2=B4m asking is because I=C2=B4ve always thought that if you add a= cache > device to the pool, the maximum size of L2ARC would be the size of the > disk you=C2=B4ve added, but recently I=C2=B4ve come to know that=C2=B4s n= ot the case. > > Here=C2=B4s a 9.3-RELEASE system that has 64 GB RAM and two 256 GB large > SSD's added as cache, that I would=C2=B4ve thought only could=C2=B4ve gro= wn to > about 512 GB: > # sysctl -n kstat.zfs.misc.arcstats.l2_size > 7696626233344 > > Another system running 9.2-RELEASE with 32 GB RAM + 240 GB SSD: > # sysctl -n kstat.zfs.misc.arcstats.l2_size > 1400038980608 > > The servers are running a software for graphing so I have seen that the > size numbers can go up and down over time, but clearly goes over the > size of the SSD's that have been added. > > We have two more systems configured with cache devices and yet another > two systems configured without. > > The problem we have is that the four systems with cache devices (our > primary storage systems) goes completely unresponsive after different > periods of time, depending on how much RAM they have and the load they > =C2=B4ve been under, I guess. The less RAM, the more frequent they stall,= and > I=C2=B4m starting to wonder if what=C2=B4s common between them is L2ARC, = because > the other two systems without cache devices doesn=C2=B4t have those issue= s, > although they aren=C2=B4t under the same kind of load either, it=C2=B4s a= disaster > recovery system receiving zfs snapshots and the other one is our syslog > server, but still... > > What do you think, are the size numbers for L2ARC unusual, and could it > be related to the stalls we=C2=B4ve been experiencing? And if the size > numbers really are unusual, is there a way to handle it, like limit how > large the L2ARC is able to grow somehow? > > > > -- > > Med V=C3=A4nliga H=C3=A4lsningar > > > -------------------------------------------------------------------------= ------ > Karli Sj=C3=B6berg > Swedish University of Agricultural Sciences Box 7079 (Visiting Address > Kron=C3=A5sv=C3=A4gen 8) > S-750 07 Uppsala, Sweden > Phone: +46-(0)18-67 15 66 > karli.sjoberg@slu.se > _______________________________________________ > 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"