SAS And SATA RAID, Powered By Unified Serial Controllers
Let’s face it: RAID controller reviews are not the sexiest topics of discussions, especially among those not involved in IT. Yet RAID has become the backbone for virtually every server or workstation in an enterprise setting, while the list of available controllers for mainstream applications is impressive, indeed. We already looked at four 8-port RAID products last summer, and we received three more controller cards since then. We wanted to see how controllers from AMCC, Areca and LSI Corporation compare to Adaptec, Atto, ICP and Ciprico/Raidcore Compare Prices on RAID Controllers.
RAID controllers with four to eight SAS or SATA ports are considered entry-level products, as they’re usually affordable and flexible, and they deliver sufficient performance to cover a plethora of common applications for small- and medium-sized enterprises.
SAS controllers are more flexible than SATA-only products, because it is possible to attach SAS and SATA hard drives to a SAS controller, while SATA controllers only work with SATA hard drives. For this reason, SAS controllers are often referred to as Unified Serial Controllers and they often inherit the management feature of their SCSI predecessors. In the end, it is possible to run both high-performance SAS drives as well as high-capacity SATA drives with the same controller.
Replacing the parallel SCSI bus with the serial point-to-point SAS/SATA interconnect facilitated creation and maintenance of RAID setups from a physical perspective: SAS and SATA cables have only few wires, which makes them cheaper and more robust than the 68-wire ribbon cables for SCSI. And SAS/SATA also widened a bottleneck: in the case of a parallel bus such as Ultra320 SCSI, the total bandwidth of 320 MB/s has to be shared by all devices, while SATA/300 or SAS at 300 MB/s provides the bandwidth for each drive.
There are many storage vendors battling for share in the mainstream business segment. Adaptec and LSI Corporation certainly are the best known, as these two companies have been storage experts ever since storage became a business sector. Firms such as ICP and AMCC/3Ware have also been around for a while. Raidcore has made an impact with its most flexible host-based RAID solution. Areca and Atto are making headway in this sector as well. But whose technology comes out on top?