Configure a RAID with an External PCI-X SAS Controller Card
A RAID (redundant array of independent disks) can improve read and write performance of storage drives so that your crucial data is always protected. A SAS HBA is an option for facilitating such an arrangement, and a free PCI-X connection on your motherboard is one way to connect this kind of RAID controller.
What is an external SAS interface card?
SAS stands for serial attached SCSI, a means by which multiple storage devices, including hard drives, are combined into a single logical unit. This is done in order to achieve faster read and write speeds and/or make stored data redundant. These particular controller cards connect to a mainboard via a PCI-X slot or an appropriate adapter. The term external distinguishes these components from internal solutions; it means that the SAS, SATA, and other connectors are accessed externally for convenient attachment and detachment of cables. Brands that make these products include:
- LSI
- IBM
- Intel
- Areca
- Adaptec
Are different SAS versions available?
Yes. There are four distinct versions of SAS. All versions offer optional support for SATA and are differentiated by their theoretical throughput. All Serial Attached SCSI devices are backward- and forward-compatible, but connections will be limited to the highest speed supported. Adapter types, such as PCI, PCI-X, or PCI-e, are suitable to all versions. The four versions are:
- SAS-1: Supports speeds up to 3 Gbps.
- SAS-2: Supports speeds up to 6 Gbps.
- SAS-3: Supports speeds up to 12 Gbps.
- SAS-4: Supports speeds up to 22.5 Gbps.
What is PCI-X?
PCI is short for peripheral component interconnect. This is a means through which expansion cards, such as these external RAID controllers, are added to a computer system. PCI-X, short for PCI extended, allows for more bandwidth than the original. PCI-X has been succeeded by PCI Express. It’s possible to use an adapter to connect these SAS HBA or host bus adapter cards.
Can you connect SATA drives to SAS controllers?
It depends on the external controller. Note that SATA support is an optional component of SAS, and a particular brand or HBA model doesn’t have to support SATA for RAID or any other purposes. If the external controller you choose does support it, then you just need an appropriate SATA cable connected to a SATA port or adapter on the controller.
Do these controllers support RAID and/or independent drives?
This depends on the controller brand and model as well. Note that SAS supports RAID fundamentally, but it must support pass-through, which is optional, in order to work with independent drives. Many RAID controllers do have pass-through as a feature.