From owner-freebsd-fs@FreeBSD.ORG Wed May 13 14:51:05 2009 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 808941065672; Wed, 13 May 2009 14:51:05 +0000 (UTC) (envelope-from mat.macy@gmail.com) Received: from yx-out-2324.google.com (yx-out-2324.google.com [74.125.44.30]) by mx1.freebsd.org (Postfix) with ESMTP id 224698FC2A; Wed, 13 May 2009 14:51:05 +0000 (UTC) (envelope-from mat.macy@gmail.com) Received: by yx-out-2324.google.com with SMTP id 8so375025yxb.13 for ; Wed, 13 May 2009 07:51:04 -0700 (PDT) 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:date:x-google-sender-auth:message-id:subject:from:to:cc :content-type:content-transfer-encoding; bh=hVRxvaqUwoVDz4SU4os6LiE4PXhocKjV1DuCYUisYAk=; b=BIivs1BB+KxItS9c8Hi4SgT272n4ocayN5hIV4a035pB5CJ2TEnm+c93Myje/p1baV LWEje8ZH0iVi18Q1Bnws46Bb+VrDnmR7vpdBprcQnhxtJCAscSvzlpg4H5ZXgKf/3fSS 9ChUJk7J3GNYDZ602TBBVZ5Ct5mK2wKuy3maI= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=nmC09Ipxq+IqBTB3Yxv9EcpKLzY6eNlGmDRY2cVNq3SPPebCohJDZG5K3WfiMmE9Hm CghHit8tBdljgSRchjZ2bved2w0fF6urtswZ9SVuQ0KGTpnRFiKWPFh29kPkmiPDpwS+ HZWhCAP/H9YGIWVditBzR4LsC+MqwGfKF2ZSc= MIME-Version: 1.0 Sender: mat.macy@gmail.com Received: by 10.100.10.15 with SMTP id 15mr1415057anj.8.1242226264542; Wed, 13 May 2009 07:51:04 -0700 (PDT) In-Reply-To: References: <49FC1BD0.4030306@T-Online.de> <3c1674c90905130529r70589318tf57198d24cf2bd57@mail.gmail.com> <20090513135335.GA42884@voi.aagh.net> Date: Wed, 13 May 2009 07:51:04 -0700 X-Google-Sender-Auth: 933a7d42ce8cf52c Message-ID: <3c1674c90905130751s60757be2t8039965b71c75467@mail.gmail.com> From: Kip Macy To: Ivan Voras Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: freebsd-fs@freebsd.org Subject: Re: UFS2 and SSDs 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: Wed, 13 May 2009 14:51:05 -0000 On Wed, May 13, 2009 at 7:31 AM, Ivan Voras wrote: > Thomas Hurst wrote: >> * Kip Macy (kmacy@freebsd.org) wrote: >> >>> I accidentally bought a camera-grade SSD. Random write performance >>> with UFS made it unusable. I ended up converting /usr to ZFS - since >>> which time I've been very happy with performance. >> >> Did you try gjournal on it? =A0SSD's should do better with sequential >> journal writes. > > My guess is that it won't matter - the issue is "small writes" not > "sequential writes". Gjournal will issue writes as it receives them - if > it receives a bunch of small ones, it will pass them on in the same > form, only sequential (the drive will still see a bunch of small > writes). This works well for mechanical drives because of rotational > properties but does nothing to SSDs. > > ZFS OTOH does a great deal of buffering. The benefits come from write-allocate - writes always end up being some multiple of erase blocks. With FFS the drive constantly has to GC partial blocks. -Kip --=20 When bad men combine, the good must associate; else they will fall one by one, an unpitied sacrifice in a contemptible struggle. Edmund Burke