From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ric Wheeler Subject: Re: Some very basic questions Date: Wed, 22 Oct 2008 09:27:55 -0400 Message-ID: <48FF2A5B.80108@redhat.com> References: <20081021132322.271ad728.skraw@ithnet.com> <48FDD710.5050702@hp.com> <20081021190136.89b2c6af.skraw@ithnet.com> <20081021171513.GA8799@infradead.org> <48FE11F9.7040700@gmail.com> <20081022142759.ac33a16c.skraw@ithnet.com> <1224681345.6448.4.camel@think.oraclecorp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: Stephan von Krawczynski , Christoph Hellwig , jim owens , linux-btrfs@vger.kernel.org To: Chris Mason Return-path: In-Reply-To: <1224681345.6448.4.camel@think.oraclecorp.com> List-ID: Chris Mason wrote: > On Wed, 2008-10-22 at 14:27 +0200, Stephan von Krawczynski wrote: > >> On Tue, 21 Oct 2008 13:31:37 -0400 >> Ric Wheeler wrote: >> >> >>> [...] >>> If you have remapped a big chunk of the sectors (say more than 10%), you >>> should grab the data off the disk asap and replace it. Worry less about >>> errors during read, writes indicate more serious errors. >>> >> Ok, now for the bad news: money is invented. >> If you replace a disk before real failure you won't get replacement from the >> manufacturer. That may sound irrelevant to someone handling 5 disks, but is >> significant if handling 500 or more. The replacement rate is indeed much >> higher than people think from their home pcs. >> > > Hardware vendors already do replace disks based on policies defined by > their own array hardware. These are already predictive. > > -chris > > > > One key is not to replace the drives too early - you often can recover significant amounts of data from a drive that is on its last legs. This can be useful even in RAID rebuilds since with today's enormous drive capacities, you might hit a latent error during the rebuild on one of the presumed healthy drives. Of course, if you don't have a spare drive in your configuration, this is not practical... ric