Am 25.03.2010 18:45, schrieb Asdo:
quoted text
> David Lethe wrote:
>> On Mar 25, 2010, at 11:20 AM, Andrew Dunn wrote:
>>  
>>> Recently Dell is selling their WD20EARS (2TB) for 90$
>>>
>>> This being one of the best PPG (Price Per Gigabyte) snatches I have
>>> seen, I was considering buying 8 of them for an mdadm array.
>>>
>>> Has anyone had experience with these drives?
>>>
>>> Note, they have 4K sectors.
>>>
>>> Thank you for your kind responses.
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>>
>> This is a low-cost consumer disk that is rated for a whole 2400 hours
>> use in a year.  You get what you pay for. 
>
> I think the "I" in RAID stands for inexpensive :-P
> Jokes apart, don't you think frequent scrubbing (e.g. weekly for a
> raid-6 or 2/week for raid-1/10) is enough to compensate for this?
> I would be way more concerned with ERC / TLER if it proves to be
> nonsettable, but I might be wrong

Just for those who like to read: ERC is a feature stated in the
ATA-specifications, that's why the "quick hack" for smartctl was so
easy.  But in the specs it is also noted, that the change a
SCT-ERC-Command does will not survive a power cycle.

So y'all will probably need some udev-triggered daemon, which runs upon
connecting a disk, checking if this disk is conforming to the ata-spec,
then finding out if it's part of a raid array.  If all answers yield
"yes", it should call SCT-ERC with a configurable value, and probably
some other "configure the drive"-commands (for tuning the idle timeout
of wdXXears).

I'll have to think about that as a project again ...

All the best,
Stefan

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