SCSI vs SATA? Is SCSI "actually" better? [closed]
For SATA, you need to be careful about using a consumer drive if you are building a RAID array.
Some power saving features and in the case of Western Digital, some of their SATA drives have a "deep recovery" process when an error is detected. These can cause a SATA RAID member to be dropped or marked as failed if it is unresponsive beyond the timeout period.
When a SATA RAID5 volume with huge drives drops a member, it is not uncommon for the rebuild to take several hours. During this time, performance will be abysmal.
Western Digital - difference between Desktop edition and RAID (Enterprise) edition hard drives? http://wdc.custhelp.com/cgi-bin/wdc.cfg/php/enduser/std_adp.php?p_faqid=1397
http://en.wikipedia.org/wiki/Time-Limited_Error_Recovery
For the sake of simplicity when I say "SCSI" I'm talking about "traditional" SCSI and SAS
So, on the most basic level SCSI drives will be more reliable simple because they are built better. They are designed and priced to be put into high end machines - primarily servers where they will get a lot of abuse and quite possibly run 24/7/365 for 5-7 years. They are made of higher quality parts, etc. SATA drives are CONSUMER GRADE drives. They are made as cheaply as possible and are not designed with the kind of workloads Servers typically do in mind.
Just as an example, you wouldn't (well some may try but ... ) grab an off the shelf linksys router and try to push 100Mbps of internet traffic from 2000 clients through it.
As far as speed, you will actually see a fairly big difference in speed just do to the spindle speeds of the SCSI devices being so much higher. You're talking 7200 RPM vs 15k RPM on the high ends of both devices. The faster spindle speed, gives you lower latency and higher access speeds. The disk can push data out ... faster.
Deciding on the Drive to put into your machine is a lot more than the theoretical maximum data rate speeds of the interface. With SCSI drives you will get closer to that than with SATA drives.