I recently bought 40 drives of the Western Digital 2 TB "Caviar Green"
variety (WD20 EARS). So far, 8 of them are "bad" inasmuch as they have
unrecoverable bad sectors, or simply won't mount. In several cases,
this began as the drive having no bad sectors, but just getting very
very slow. A "normal" one of these drives will easily get 25 MB/s or
more sustained transfer rates, but the first sign of trouble is that
this rate drops to ~1 MB/s or less. Eventually, you start seeing bad
sectors, and these continue to increase until the drive becomes unusable.
Just a guess, but what I think is going on is that most drives these
days have an internal reserved area for re-mapping bad sectors. I
imagine this re-mapping slows things down, but no bad sectors are
reported. This could all just be a particle of dust floating around
inside, and once you make one scratch, that makes more bits of dust. etc.
Yes, there are more expensive drives that are "server certified" and
cost twice as much. Note that at 25 MB/s it takes about a day to simply
read-check all 2e12 bytes on the drive, and about a week to do a full
"badblocks" run. This may be why "better" drives are more expensive. A
colleague of mine here bought a few of those, but one of them is now in
my "BAD" pile. Transfer rate suddenly slowed down to ~2 MB/s.
Sigh. Technology just doesn't work.
-James Holton
MAD Scientist
On 10/27/2010 1:43 AM, Frank von Delft wrote:
> I've been told by my (frighteningly geek-competent) colleague that
> the platters are identical, but the cheaper ones are those at the
> bottom of the Quality Control pile, which are therefore spun more
> slowly, and don't get any claims of reliability.
>
> (Have you checked the disk rotation speed? I imagine the Dell ones go
> much faster.)
>
> phx
>
>
> On 27/10/2010 02:52, Edward A. Berry wrote:
>> Another question about computer hardware- If I configure a computer
>> at the
>> Dell site, it costs about $700 to add a 2TB SATA drive.
>> On amazon.com or Staples or such, a 2TB drive costs ~$110. to $200
>> depending on brand.
>>
>> Are the Dell-installed drives much faster, or more reliable, or have
>> a better warranty? After all, RAID is supposed to stand for redundant
>> array of inexpensive disks, and we could afford a lot more redundancy
>> at the Amazon.com price.
>>
>> And, are there any brands or models that should be avoided due to known
>> reliability issues?
>>
>> Thanks,
>> eab
|