Q: How does the performance of SATA in RAID compare to SCSI in RAID? A: Over the past several years there have been many improvements to SATA and RAID, including RAID on a chip (ROC) embedded on server motherboards, as well as adapters. Some of the improvements beyond performance, lower cost and reduced power consumption include acceleration of RAID 6, more cache memory, and support for SAS and SATA intermix. Generally speaking, the SAS disk drives will perform better than the SATA disk drives. Keep in mind that from a performance standpoint you may be comparing apples to oranges with SATA vs. parallel SCSI, as well as different adapters. Also, some ROCs or adapters are tuned for high-throughput reads or writes, while others may be tuned for lots of small I/O operations. For performance numbers, check out the Web sites of AMD, Applied Micro Circuits, Atto Technology, Intel and LSI, among others. --Greg Schulz, founder and senior analyst, StorageIO Group