Date: Sun, 3 Mar 2013 15:20:43 +1100 From: Peter Jeremy <peter@rulingia.com> To: deeptech71 <deeptech71@gmail.com> Cc: freebsd-current@freebsd.org Subject: Re: access to hard drives is "blocked" by writes to a flash drive Message-ID: <20130303042043.GH286@server.rulingia.com> In-Reply-To: <51323712.5000406@gmail.com> References: <51323712.5000406@gmail.com>
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--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 <deeptech71@gmail.com> 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--
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