Re: md-raid and block sizes

On Tue, 28 Dec 2010 18:29:26 +0700
hansbkk@gmail.com wrote:

This doesn't actually relate to the blocksize issue, but a caveat -
I've heard that these "green" drives are not suitable for use in a
RAID.

The specific issue is apparently that these drives spin down very
frequently, but most RAID implementations keep spinning them back up
again just as frequently (perhaps unnecessarily?), thus causing undue
wear and tear on the drives' mechanics and ultimately premature
failure.

Of course this could be spin from the vendors to get people to spend
more money on the "enterprise" level drives - I personally am a firm
believer in saving money by buying consumer-level hardware and using
the savings to buy extra redundancy.

It just so happens that I've bought a batch of Samsung 2TB drives for
a RAID6 I'm building, and it turns out they are quite similar to the
WDEARS, both in their use of "new format" 4K blocks and some of the
green features. I haven't yet detected any undue drive
stopping/starting, but then again they are so quite I'm not sure how
to check. . .

Confirmation or refutation of these thoughts would be most welcome.

This all is just FUD and you shouldn't repeat and spread it further, helping
the vendor's marketing department get people spend money on an "Enterprise"
sticker.

WD*EARS/EADS, or at least most older models in that line-up, do indeed unload
their heads after a short period of time, however that in no way inhibits their
usage in RAID (with this issue there's no difference at all, RAID or no RAID),
and is user-adjustable using the WDIDLE3 utility:
https://encrypted.google.com/search?q=WDIDLE3

Samsung drives do not have any spindown/load/unload problems, but be aware of
this: http://sourceforge.net/apps/trac/smartmontools/wiki/SamsungF4EGBadBlocks

-- 
With respect,
Roman