Re: Use of WD20EARS with MDADM

[Simon Matthews <simon.d.matthews@gmail.com>]

On Wed, Apr 21, 2010 at 6:20 AM, Bill Davidsen <davidsen@tmr.com> wrote:
> Phillip Susi wrote:
>>
>> On 4/14/2010 3:53 PM, Bill Davidsen wrote:
>>
>>>
>>> Stefan *St0fF* Huebner wrote:
>>>
>>>>
>>>> Am 25.03.2010 18:45, schrieb Asdo:
>>>>
>>>>>
>>>>> 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?
>>>>>>>
>>
>> I believe that these disks only come in the "green" variety.  I recently
>> picked up a 1.5 tb version for testing and cheap bulk storage, and I
>> would not suggest using them in a raid array because the green drives
>> firmware automatically parks the head after 8 seconds of inactivity and
>> reduces the rpm of the disk.  The constant parking can quickly wear out
>> the head under high use and there is no way to disable this "feature".
>>
>
> I hear this said, but I don't have any data to back it up. Drive vendors
> aren't stupid, so if the parking feature is likely to cause premature
> failures under warranty, I would expect that the feature would not be there,
> or that the drive would be made more robust. Maybe I have too much faith in
> greed as a design goal, but I have to wonder if load cycles are as
> destructive as seems to be the assumption.
>
> I'd love to find some real data, anecdotal stories about older drives are
> not overly helpful. Clearly there is a trade-off between energy saving,
> response, and durability, I just don't have any data from a large population
> of new (green) drives.


It's not hard data, but there was discussion of a similar issue fours
years ago related to load/unload cycles on laptops under Ubuntu:
https://bugs.launchpad.net/ubuntu/+source/acpi-support/+bug/59695

Simon
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html