----- Message from cody@mochamail.com ---------
     Date: Wed, 26 Dec 2007 21:22:42 -0800
     From: Cody Yellan [off-list ref]

I had a 4x500GB SATA2 array, md0.  I added one 500GB drive and
reshaping began at ~2500K/sec.  Changing
/proc/sys/dev/raid/speed_limit_m{in,ax} or
/sys/block/md0/md/sync_speed_m{in,ax} had no effect.  I shut down all
unnecessary services and the array is offline (not mounted).  I have
read that the throttling code is "fragile" (esp. with regard to
raid5) but does this make sense?  I will wait (in)patiently for it to
finish, but I do wonder why the configuration parameters have no
effect.  This is a dual quad 2GHz Xeon machine with 8GB of memory
running RHEL5.  Is this the maximum speed?

----- End message from cody@mochamail.com -----

Certainly not. I've personally used a similar setup with >80MB/s  
reshape speeds.
There must be some other limiting factor.
Try simultanous dd's from the drives, if that doesn't work as fast as  
it should there might be some bus contention?


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