From owner-freebsd-fs@FreeBSD.ORG Sun Jun 26 21:35:38 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 AE94F1065670 for ; Sun, 26 Jun 2011 21:35:38 +0000 (UTC) (envelope-from bsd@vink.pl) Received: from mail-bw0-f54.google.com (mail-bw0-f54.google.com [209.85.214.54]) by mx1.freebsd.org (Postfix) with ESMTP id 3FF838FC0A for ; Sun, 26 Jun 2011 21:35:37 +0000 (UTC) Received: by bwa20 with SMTP id 20so1272259bwa.13 for ; Sun, 26 Jun 2011 14:35:37 -0700 (PDT) Received: by 10.204.16.70 with SMTP id n6mr3616881bka.87.1309124135998; Sun, 26 Jun 2011 14:35:35 -0700 (PDT) Received: from mail-bw0-f54.google.com (mail-bw0-f54.google.com [209.85.214.54]) by mx.google.com with ESMTPS id af13sm3578590bkc.19.2011.06.26.14.35.35 (version=SSLv3 cipher=OTHER); Sun, 26 Jun 2011 14:35:35 -0700 (PDT) Received: by bwa20 with SMTP id 20so1272234bwa.13 for ; Sun, 26 Jun 2011 14:35:34 -0700 (PDT) MIME-Version: 1.0 Received: by 10.204.130.19 with SMTP id q19mr125410bks.0.1309124134869; Sun, 26 Jun 2011 14:35:34 -0700 (PDT) Received: by 10.204.120.66 with HTTP; Sun, 26 Jun 2011 14:35:34 -0700 (PDT) In-Reply-To: <4E0435B6.30004@fsn.hu> References: <4E0435B6.30004@fsn.hu> Date: Sun, 26 Jun 2011 23:35:34 +0200 Message-ID: From: Wiktor Niesiobedzki To: freebsd-fs@freebsd.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: Subject: Re: ZFS L2ARC hit ratio 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: Sun, 26 Jun 2011 21:35:38 -0000 2011/6/24 Attila Nagy : > On 06/21/11 21:59, Wiktor Niesiobedzki wrote: >> >> I've recently migrated my 8.2 box to recent stable: >> FreeBSD kadlubek.vink.pl 8.2-STABLE FreeBSD 8.2-STABLE #22: Tue Jun =C2= =A07 >> 03:43:29 CEST 2011 =C2=A0 =C2=A0 root@kadlubek:/usr/obj/usr/src/sys/KADL= UB =C2=A0i386 >> >> And upgraded my ZFS/ZPOOL to newest versions. Though through my >> monitoring I've noticed some declination in L2ARC hit ratio (server is >> not busy, so it doesn't look that suspicious). I've made some tests >> today and I guess, that there might be some problem: > > Likely because vfs.zfs.l2arc_noprefetch is now 1. > > I'm running on i386 so prefetch for me was always disabled. It turns out, that the "bad" behaviour is a result of putting: vfs.zfs.prefetch_disable=3D0 In loader.conf I thought that this is somehow better in ZFS v28, than in v15. Anyhow, it looks like prefetching shall be left disabled for now. Cheers, Wiktor Niesiobedzki