Date: Wed, 3 Aug 2016 16:59:13 +0100 From: Arthur Chance <freebsd@qeng-ho.org> To: Jon Radel <jon@radel.com>, "Brandon J. Wandersee" <brandon.wandersee@gmail.com> Cc: "William A. Mahaffey III" <wam@hiwaay.net>, FreeBSD Questions !!!! <freebsd-questions@freebsd.org> Subject: Re: Ominous smartd messages .... Message-ID: <c20fef42-b57c-6842-0de8-0e9418ee7d50@qeng-ho.org> In-Reply-To: <7f1afc31-7eda-ba4c-41ea-046a091d6055@radel.com> References: <e5a65f8a-27a0-65e7-42db-28bef824e0c0@hiwaay.net> <117bb75c-aa6a-d562-c971-d0bab742f5ad@radel.com> <8637mmdkah.fsf@WorkBox.Home> <7f1afc31-7eda-ba4c-41ea-046a091d6055@radel.com>
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On 03/08/2016 15:09, Jon Radel wrote: > On 8/3/16 10:00 AM, Brandon J. Wandersee wrote: >> >> Jon Radel writes: >> >>> I've read reasonable sounding commentary from people running very, very >>> large collections of hard drives that there is a high enough correlation >>> between this error and the drive going to heck sooner rather than later >>> that they take this as a sign to replace. [Can't find reference right now.] >> >> While there's no way to know from the error message alone just what will >> happen to the disk in the coming days, the general reasoning is this: >> sectors are not physically segregated. They all sit on the same >> platter. Several bad sectors occuring in a short period might be a sign >> of physical fault in the platter, and if that fault is real then stress >> from the platter spinning will likely cause that fault to spread. So >> some people conclude that the appearance of several bad sectors in a >> short period should just be a signal to replace the disk immediately. >> > > If I remember the discussion well enough (sad that I can't find it) my > use of "correlation" was precise. They actually manage enough drives > (thousands) and kept enough records to allow for statistical analysis > which indicate that this smartd error correlates very well with failure > within [I wish I could remember] timeframe. > > Do please excuse the utter lack of footnotes. :-( > I think everyone is probably thinking of Backblaze. This is their latest summary of drive statistics https://www.backblaze.com/blog/hard-drive-failure-rates-q2-2016/ And this is their take on which SMART metrics matter https://www.backblaze.com/blog/hard-drive-smart-stats/ -- Moore's Law of Mad Science: Every eighteen months, the minimum IQ necessary to destroy the world drops by one point.
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