Re: ZFS with Linux: An Open Plea
From: Matt Mackall
Date: Fri Apr 27 2007 - 18:11:56 EST
On Thu, Apr 26, 2007 at 10:21:02PM -0700, Valerie Henson wrote:
> On Wed, Apr 18, 2007 at 01:25:19PM -0400, Lennart Sorensen wrote:
> > Does it matter that google's recent report on disk failures indicated
> > that SMART never predicted anything useful as far as they could tell?
> > Certainly none of my drive failures ever had SMART make any kind of
> > indication that anything was wrong.
> I saw that talk, and that's not what I got out of it. They found that
> SMART error reports _did_ correlate with drive failure.
In fact, a certain small set of SMART indicators were a very good sign
that a drive would fail.
> However, they found that the correlation was not strong enough to make
> it economically feasible to replace disks reporting SMART failures,
> since something like 70% of disks were still working a year after the
> first failure report. Also, they found that some disks failed without
> any SMART error reports.
Indeed, SMART registered no counts at all for most failures, so on the
whole, it can't be said that SMART can predict failures.
So: not a good idea to base your backup scheme on SMART warnings, but
not entirely useless.
Mathematics is the supreme nostalgia of our time.
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