From owner-freebsd-questions@FreeBSD.ORG Wed Jan 13 18:35:34 2010 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 2EFD81065676 for ; Wed, 13 Jan 2010 18:35:34 +0000 (UTC) (envelope-from ivoras@gmail.com) Received: from mail-ew0-f211.google.com (mail-ew0-f211.google.com [209.85.219.211]) by mx1.freebsd.org (Postfix) with ESMTP id ACF898FC16 for ; Wed, 13 Jan 2010 18:35:33 +0000 (UTC) Received: by ewy3 with SMTP id 3so19945806ewy.13 for ; Wed, 13 Jan 2010 10:35:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:from:date:x-google-sender-auth:message-id:subject:to:cc :content-type:content-transfer-encoding; bh=j7F7r+nYCEsURYL//weH31OQF+A4aFW1aMZxTe7mKcE=; b=PjhcSEcMQu7hN9HyBOKTKrK9BAafLocVnzNfs1cb04nIWYDN5jpO6FdUnCPYpAG50K eIoJXHZdz0mOyTdHgorZAXSOxoWnujIQCE8ezeGVDEE2pZ4KUUEv71P46Bol++op9aYj GH4bx6bbDFY+rjvQfWc8pK0jzR4RA/+eRLGIc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:cc:content-type :content-transfer-encoding; b=Lp8Q+CpiJlW2quSpsVhnTQaQd95/YGnp25JN5vCzcHdr64QLxlh3RaaCsY8fLlP+on 8PCYYnyXTdzVJjyNSb03AxE6IJm4xT4buThCSgwR/W7zEMHNNwT61pIs/ITsBpTMLlHH lSY6Bxs1MvVADP1PP79O2tKYXRZ1HY8Cmz+Rc= MIME-Version: 1.0 Sender: ivoras@gmail.com Received: by 10.216.93.66 with SMTP id k44mr130444wef.67.1263407721446; Wed, 13 Jan 2010 10:35:21 -0800 (PST) In-Reply-To: References: <8418112cdfada93d83ca0cb5307c1d21.squirrel@email.polands.org> From: Ivan Voras Date: Wed, 13 Jan 2010 19:35:01 +0100 X-Google-Sender-Auth: 71363d7eb71f8fe8 Message-ID: <9bbcef731001131035x604cdea1t81b14589cb10ad25@mail.gmail.com> To: Doug Poland Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: freebsd-questions@freebsd.org Subject: Re: 8.0-R-p2 ZFS: unixbench causing kmem exhaustion panic X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 13 Jan 2010 18:35:34 -0000 2010/1/13 Doug Poland : > > On Wed, January 13, 2010 11:55, Ivan Voras wrote: >> Doug Poland wrote: >> >>> So the question is, can ZFS be tuned to not panic or hang no matter >>> what I throw at it? >> >> Apparently not. >> >> =C2=A0> I began with a system with no tunables in /boot/loader.conf >> =C2=A0> (vm.kmem_size and vm.kmem_size_max). =C2=A0Then I tried increasi= ng >> =C2=A0> vm.kmem_size and vm.kmem_size_max a GB at a time, until I was at >> 4GB. >> >> Try adding vfs.zfs.arc_max=3D512M to /boot/loader.conf. >> > Would you suggest tweaking the vm.kmem_size tunables in addition to > arc_max? No, unless they auto-tune to something lesser than approximately arc_max*3. I try to set arc_max to be a third (or a quarter) the kmem_size, and tune kmem_size ad_hoc to suit the machine and its purpose. The reason for this is that "arc_max" is just a guideline, not a hard limit... the ZFS ARC usage can and will spike to much larger values, usually in the most inopportune moment.