From owner-freebsd-current@FreeBSD.ORG Sun Mar 3 04:20:54 2013 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 7C8948D5 for ; Sun, 3 Mar 2013 04:20:54 +0000 (UTC) (envelope-from peter@rulingia.com) Received: from vps.rulingia.com (host-122-100-2-194.octopus.com.au [122.100.2.194]) by mx1.freebsd.org (Postfix) with ESMTP id D913D283 for ; Sun, 3 Mar 2013 04:20:52 +0000 (UTC) Received: from server.rulingia.com (c220-239-237-213.belrs5.nsw.optusnet.com.au [220.239.237.213]) by vps.rulingia.com (8.14.5/8.14.5) with ESMTP id r234KnXv026142 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Sun, 3 Mar 2013 15:20:50 +1100 (EST) (envelope-from peter@rulingia.com) X-Bogosity: Ham, spamicity=0.000000 Received: from server.rulingia.com (localhost.rulingia.com [127.0.0.1]) by server.rulingia.com (8.14.5/8.14.5) with ESMTP id r234Ki2T056927 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sun, 3 Mar 2013 15:20:44 +1100 (EST) (envelope-from peter@server.rulingia.com) Received: (from peter@localhost) by server.rulingia.com (8.14.5/8.14.5/Submit) id r234KhkF056926; Sun, 3 Mar 2013 15:20:43 +1100 (EST) (envelope-from peter) Date: Sun, 3 Mar 2013 15:20:43 +1100 From: Peter Jeremy To: deeptech71 Subject: Re: access to hard drives is "blocked" by writes to a flash drive Message-ID: <20130303042043.GH286@server.rulingia.com> References: <51323712.5000406@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="O3RTKUHj+75w1tg5" Content-Disposition: inline In-Reply-To: <51323712.5000406@gmail.com> X-PGP-Key: http://www.rulingia.com/keys/peter.pgp User-Agent: Mutt/1.5.21 (2010-09-15) Cc: freebsd-current@freebsd.org X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 03 Mar 2013 04:20:54 -0000 --O3RTKUHj+75w1tg5 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2013-Mar-02 18:29:54 +0100, deeptech71 wrote: >When one of my flash drives is being heavily written to; typically by >``svn update'' on /usr/src, located on the flash drive; the following >can be said about filesystem behavior: > >- ``svn update'' seems to be able to quickly update a bunch of files, > but is then unable to continue for a period of time. This behavior > is cyclical, and cycles several times, depending on the amount of > updating work to be done for a particular run of ``svn update''. This sounds like normal flash behaviour: You can only write to erased blocks. The SSD firmware attempts to keep a free pool of erased blocks but if you write too fast, you empty the free pool and need to wait for the wear-levelling algorithm to move blocks around and erase them. Enabling TRIM (the '-t' flag on tunefs) will help if the drive supports TRIM (if it doesn't, it'll probably just lockup). Otherwise, you need to either put up with it or upgrade to a better SSD. I run into this regularly with the low-end SuperTalent drive in my Netbook but have never seen it with the OCZ Agility4 that I use for L2ARC in my fileserver. --=20 Peter Jeremy --O3RTKUHj+75w1tg5 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) iEYEARECAAYFAlEyz5sACgkQ/opHv/APuIepRwCgq4di5e+pL8o+ePdFM1SB9cE0 FsoAn0VHmyOLoTUPFsXPVauG6t6iYyYF =8t5b -----END PGP SIGNATURE----- --O3RTKUHj+75w1tg5--