On Fri, Jun 18, 2010 at 08:30:53AM +1000, Neil Brown wrote:

2-drive RAID10 f2  would be expected to provide better read throughput
(possibly twice as fast) at some cost to write throughput.  For many people
this is a worthwhile trade-off.  So it might be better for you.
Read throughput would degraded down to write throughput (i.e. slower than
RAID1) if the RAID10 were degraded.

The slowdown of write thruput is on the raw raid, and on file systems
without elevator algorithms. If you employ a file system with an
elevator algorithm, then there will be no noticeable slowdown for
writes, as witnessed by many benchmarks.

best regards
keld