BANGALORE, INDIA: For all the recent interest that surrounds Serial Attached SCSI (SAS), it is not a new technology. Neither is it a brand new concept. However, it has come a long way in the past few years

The word 'serial' comes from the use of point-to-point serial protocol to transfer data. This replaces the slower parallel SCSI bus technology that appeared in the mid-80s. The same concept is now used for the next generation of ATA drives: Serial ATA.

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Enterprise disks with SAS interfaces have been shipping since 2004. They began life as replacements of hard disk drives within servers, rapidly replacing the slower SCSI drives. 

With the availability of 3Gbps and 6Gbps SAS, performance is now on par with fibre channel (FC) design and in highly random read environments can outperform FC, all of which has re-ignited the question of whether SAS will replace FC.

SAS or FC: Which way to go?
This tussle between SAS and FC has been played out in the media and technical circles for sometime.

FC is entrenched in the enterprise storage space and replacing it may not be that simple. But SAS is already seeing interest in both large enterprises and small and medium enterprise market space.

While SAS technology not only continuous to demonstrate better price performance ratio, it also reduces the power and space consumption up to 40 percent thus reducing total TCO.

According to IDC 2009 projections for worldwide HDD shipments for Enterprise Applications, 2008-2012, SAS drive shipments are slated to increase in the next three years while FC drive shipments are expected to decline.

It is not just analysts who are projecting SAS’ rise at the expense of FC. Today’s disk vendors are also planning to limit their development of new FC disks in the next few years. Which means that FC disk development will be capped at 600GB and a 4Gbps interface.

Meanwhile, SAS drives are expected go beyond 6Gbps (See table for the benefits of 6Gbps SAS drives).

6Gbps SAS features, benefits

Source: SCSI Trade Association