That kind of sounds like a incompatability with the SAS expander. Find out what model of SAS expander for sure. I have tested the 1880 and 1882 with the 6 GB LSI expander and I know it works for sure (it doesn't with the 3 GB one).

Did you change the percentage of background rebuild percentage so it is 80% instead of the default 20%? That will affect the speed of a background init by a large amount. I have found the ARC-1882 is very fast though. With 80% setting I have seen the ARC-1222 init 24x3TB ultrastar 7200 RPM hitachi disks in just over 8 hours (very fast) but it was a foreground init which makes it go quite a bit faster.

For example my ARC-1880 with 30x3TB 5700 RPM coolspin hitachi's did a *background* init in:

2011-09-04 05:21:17 DATA 2 VOLUME Complete Init 040:39:42


The rebuild was quite a bit faster though and took about 25 hours. Granted this is a *huge* 90TB array.