Date: Sun, 03 Apr 2011 18:20:27 +0100 From: Bruce Cran <bruce@cran.org.uk> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: freebsd-stable@freebsd.org Subject: Re: Constant rebooting after power loss Message-ID: <4D98AC5B.1050606@cran.org.uk> In-Reply-To: <201104020335.p323Zp8Q018666@apollo.backplane.com> References: <87d3l6p5xv.fsf@cosmos.claresco.hr> <AANLkTi=kEyz-mKLzdV8LAf91ZhMTP8gLKs=3Eu5WD8mh@mail.gmail.com> <874o6ip0ak.fsf@cosmos.claresco.hr> <7b15d37d28f8ddac9eb81e4390231c96.HRCIM@webmail.1command.com> <AANLkTi=KEwmm1hM6Z=r_SWUAn9KhUrkTVzfF6VmqQauW@mail.gmail.com> <14c23d4bf5b47a7790cff65e70c66151.HRCIM@webmail.1command.com> <AANLkTi=6pqRwJ96Lg=603cYg_f8QUXkg8aXtbjbYpFrV@mail.gmail.com> <201104020335.p323Zp8Q018666@apollo.backplane.com>
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This is a cryptographically signed message in MIME format. --------------ms080506010204030007090301 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable On 02/04/2011 04:35, Matthew Dillon wrote: > First, a power loss to the drive will cause the drive's dirty writ= e cache > to be lost, that data will not make it to disk. Nor do you really= want > to turn of write caching on the physical drive. Well, you CAN tur= n it > off, but if you do performance will become so bad that there's no = point. > So turning off the write caching is really a non-starter. Do you know if that's changed at all with NCQ on modern SATA drives?=20 I've seen people commenting that using tags recovers most, if not all,=20 of the performance lost by disabling the write cache. --=20 Bruce Cran --------------ms080506010204030007090301--
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