The SAS (Serial Attached SCSI) interface standard is the latest evolution of the SCSI standard. SAS is a serial interface for transferring data point-to-point between hardware devices. As such, a SAS storage interface offers advantages over its SCSI predecessor which is a parallel interface. As an evolution of SCSI, SAS uses the established SCSI command set, but cabling and connectors are not the same between the two interfaces due to the differences inherent in serial and parallel buses. Notably, SAS is backward compatible with the SATA (Serial ATA) interface which has been adopted widely by hard drives in the last decade. Consequently, many SAS storage solutions include a mix of cost-effective SATA drives and higher performance SAS drives.
Servers and drives using SAS offer the best performance and most flexibility to build an enterprise-level storage solution today. This is mainly afforded by the advantages from using the SAS interface. Some of the key advantages are:
Expandability and scalability — SAS storage can support a large number of devices due to the design of the SAS interface. Using SAS expanders, each SAS domain can theoretically support up to 16,384 devices. This support for a large number of devices allows storage solutions to have a large margin for drive expansion. With the use of SAS backplanes, drives can be hot-pluggable and be easily installed or removed.
High transfer speeds — SAS drives currently in the market implement SAS 2.0 and SAS 3.0. These specifications enable data transfer speeds of 6Gb/s and 12Gb/s respectively. These speeds are among the fastest available in the industry for mass market storage devices. SAS storage that uses SAS solid-state drives benefit from high data transfer speeds as the low latency flash memory in these drives will have a lower chance of being bottlenecked by the I/O interface.
Built-in redundancy — Each SAS drive has two data ports, and each port can be configured to be in separate SAS domains. In effect, the data in a SAS storage drive can be accessed through two separate and redundant paths. If one path goes down (from a server failure, for example), data can still be accessed through the other path thereby enabling complete failover redundancy for the drive.
Flexibility — SAS host adapters are backward compatible with SATA drives. Hence, SATA drives can be connected to servers with SAS host adapters and to SAS expanders and backplanes. However, this flexibility is not offered by SATA as SAS drives cannot be connected to SATA host adapters. SAS storage can also be used in a large variety of RAID implementations enabling concurrency, dynamic load balancing, and failover when more than one RAID controller is used. Storage systems such as network attached storage using both SAS and RAID can provide for many configuration options and topology designs.
Thinkmate is a premier supplier of rack mount servers including storage servers. Thinkmate’s range of STX servers and JBOD enclosures for cloud, nearline, and enterprise storage includes a large variety of configurations using SAS host controllers and drives. Thinkmate’s highly interactive and user-friendly website allows a data storage solution to be configured from scratch using STX rack mount server chassis, Intel® Xeon® or AMD Opteron™ CPUs, SAS 6Gb/s and 12Gb/s controllers and drives, SATA controllers and drives, 7,200/10,000/15,000 RPM hard drives, solid-state SAS drives, and Windows or Linux-based operating systems. Custom storage solutions using SAS storage can also be created for you by Thinkmate’s expert configurators and in-house solution engineers. Each STX storage server or JBOD enclosure purchased from Thinkmate comes with a 3-year warranty with advance parts support and 24-hour customer support.