DO NOT BUY Western Digital "Green" Drives (also present in WD "Elements" external USB cases)
just a word of warning: on absolutely no account, not for any reason,
should you buy WD "Green" drives.
i've just spent a hair-raising 6 weeks discovering that these drives,
when pushed above a mere 40 Centigrade, become so unstable that they
can actually become completely unresponsive, shut down, and leave the
linux kernel in a completely unstable state, especially if they are
part of a RAID1 mirror.
it merely takes something such as .... ooo, copying the data? or...
shock, horror, writing a file, to raise the temperatures enough to
cause them to become unstable. and as for actually doing a RAID check
or a RAID1 re-join - well, you know how normally the mdadm mismatch
count is supposed to be zero? well, by the time the re-build is
complete, the mismatch count is up to 170,000.
now, you may be thinking "surely, that was just unlucky with two
drives, right?" wrong - the total number of drives used for this RAID1
mirror was *four* drives [cf: earlier very helpful discussion
involving a script which someone published - thanks! - that detected
partly-complete RAID mirrors]
so, whilst most people are finding that these drives are "great", the
reality is that they are only "fantastic" if you don't actually use
them. the moment you try to do a backup of them (for example if
they're failing) then it is too late: you will be absolutely
guaranteed to have lost all the data.
according to the mdadm mismatch count as a standard heuristic /
guideline to determine whether drives should be replaced, strictly
speaking, these drives are already end-of-life. but being sold as
now, apparently, what Western Digital do is they test new drives
thoroughly, and if they pass with flying colours, they are labelled
"black" and sold for more money. if they fail, then they're
"re-programmed" to run a bit slower, thus making less noise, use less
power, and can therefore justify being sold with a "green" label.
unfortunately what that means is that Western Digital are knowingly
selling faulty drives, *knowingly* trying to pass off
unfit-for-purpose drives as "new".
if you have purchased WD "Elements" or any other "Green" Drives, you
should perform a SLOW backup, ensuring that the temperature never goes
above 38C in the process, and return them as "unfit for purpose" to
wherever you bought them from.
by contrast, hitachi's 1.5tb drives which were £70 each off of ebuyer
(instead of £55 for the WD Elements including the external USB case)
run consistently at a full FOUR degrees centigrade lower temperature,
even when the WD Green Drive was removed from its USB case and placed
into the exact same server in which the hitachi drive was present.
four identical WD Elements drives - all of them completely unfit for
purpose. that's not an accident, and i am not the only person who has
experienced difficulties with these drives (different batch, different