[CentOS] info about hdds in raid

Boris Epstein borepstein at gmail.com
Tue Nov 3 14:44:58 UTC 2009

On Mon, Nov 2, 2009 at 7:02 PM, Les Mikesell <lesmikesell at gmail.com> wrote:
> John R Pierce wrote:
> > Les Mikesell wrote:
> >> If you can see activity lights, you can 'cat /dev/sd? >/dev/null' to
> >> make them busy, one at a time (where ? is a, b, c, etc).
> >>
> >
> > hahaha, I've done that, only my version is...
> >
> >     # dd if=/dev/sdX of=/dev/null bs=512
> >
> > but, same difference
> It's unfortunately about the best we've got when device names are
> assigned more or less randomly.  NICs are even worse - we need a command
> to make the lights blink there too.
> --
>   Les Mikesell at gmail.com
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Fully second that. The dd read test is the best way to tell which
drive is starting to fail. As soon as one does it is not a bad idea to
replace it.

Note that sometimes SMART drive and such technologies fail to detect
missing sectors even when the dd test stumples upon them.


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