Re: disk arms (was RE: Tips for user ASP)

I'm also no guru, but I ran into a problem that I thought I should pass on:

Mixing drive sizes in the same ASP --- DON'T DO IT!

I have a client that had 8x4gb drives and wanted to add some more.  We ordered
some 4gb drives and by mistake they sent 3x4gb and a 8gb.  We called them up and
they said to just keep it.  It would cost everyone more to ship back, restock,
send proper part, etc. than it was worth. (used market)

So we installed it.  BIG mistake.  All the writes started being made to this
single drive until it's percentage full matched the rest of the drives.

So with all the drives at about 45%, this drive gets all new writes until it
reaches 45% which means that a lot of the new data is now constrained by a
single disk arm.

Over time it has leveled itself back out again because by now that data is now
stale and new data is being spread out better, but just a word of caution.

ymmv