Danilo Godec wrote:

Some manufacturers make 'special' versions of drives for RAID (WD RE4, 
Seagate SE, ...). Apparently the main difference is in error handling, 
where normal 'desktop' drives try hard to recover an error (up to 
several minutes) while RAID drives give up quickly (few seconds) so 
that the RAID controller can take over.

not so much "special" as "different"

the term to look for is "enterprise"

you've identified the key distinction:

- desktop drives assume that they have the only copy of your data, the 
on-board processor tries very hard to read and re-read until it returns 
your data ---- the result is that everything slows down

- if you have a raid array, you want a failing disk to give up and 
return, very quickly, so that the data can be read from a different drive

I learned this the hard way, when I had a server that just slowed way 
down to the point that it took 10 seconds or more to echo a keystroke.  
It took me a long time to figure out what was going on - and some rather 
painful false starts (trashed the o/s).

One important thing I discovered:  the md RAID driver does NOT consider 
a long time delay as a signal to fail a drive out of an array.  It's a 
really good idea to run mdstat and keep an eye on your drives.  If Raw 
Reed Error goes above 0, start paying attention.

Miles Fidelman



-- 
In theory, there is no difference between theory and practice.
In<fnord>  practice, there is.   .... Yogi Berra