On Sun, 2013-07-07 at 11:45 -0500, Stan Hoeppner wrote:

Maybe an example will help.  Is a 12 drive array faster than a 10 drive
array?  Yes, of course.  If your chassis holds 12 drives and you assign
two as spares, then you have 10 drives in your array.  That's 20%
slower.  If you keep spares on a shelf and hot swap them in after
failure, you can have all 12 drives in your array and not lose that 20%
performance.

Ah... okay I see what you were talking about ... sure... but it's not
the hot swap that will (directly) degrade performance... ist because you
don't use all your slots and thereby not getting out the maxmimum
performance gain possible due to the striping...

Well of course.  By designing your storage with dissimilar drives to
avoid a rare, show stopping, firmware bug that may or may not be present
in a specific drive model, you're simultaneously exposing yourself to
other issues because the firmware doesn't match.  Performance will be
suboptimal as your drives will have difference response times.

Sure, but as said performance isn't the main goal...

Additionally, timeout and error handling will likely be different,
causing the same.  Interpreting S.M.A.R.T. data will be difficult
because each of the drives will report various metrics differently, etc,
etc.  So instead of only being required to become intimately familiar
with one drive model, you must do so for 4 or 5 drive models.

Sure..


Thanks for your comments.

Cheers,
Chris.