SAS vs SATA in MacPro

[Andrew Laurence]

At 1:24 PM -0700 4/10/08, Kevin Callahan wrote:
>this may be the wrong list - but I'm looking at setting up a RAID in 
>my new MacPro for uncompressed video capture.
>
>It was suggested I look at the Barracuda ES.2 drives.
>
>They come in SAS or SATA.
>
>Is there a reason I should choose one over the other?  When I look 
>in my profiler for the MacPro, I see that both drive types are 
>supported.

*Generally* speaking, SAS (serial-attached SCSI) is more expensive 
per GB, but faster at random read/writes of small data chunks.

*Generally* speaking, SATA (serial ATA) is cheaper per GB, but better 
at long data stripes.

Without looking at the data rate specs for each drive, and not 
knowing the characteristics of Apple's RAID controller, I'd suspect 
that SATA drives would be better for video capture.

That said, striped disks (RAID 0) are faster than single disks. 
Mirrored disks (RAID 1) provide redundancy, but no performance 
improvement.  RAID 5 stripes across all disks with distributed 
parity, but often sucks on writes because of parity calculations. 
RAID 0+1 is optimal for performance+redundancy, but expensive in 
dedicated disks due to mirroring.

-- 
Andrew Laurence
atlauren at uci.edu