We are getting to ready to purchase a Dell EqualLogic PS6100 with 24 x 900GB drives (10K). I am having a hard time deciding whether to set them up with RAID10 or RAID50, and it seems like everyone is divided on which is best. For our applications, I believe either will provide adequate performance and disk space. What concerns me is the longer rebuild times in a RAID50 array if one of the drives fails. Does anyone know if there is a formula to calulating this (one that you don't have to be Albert Einstein to calculate)? Is there really a significant difference in rebuild times for RAID10 vs RAID50? Are we talking several days vs several hours?