SAS (Serial Attached SCSI) continues to be the interface of choice for mission-critical storage sub-systems. SAS 24G is more than just a 2x speed-bump over previous generation of SAS 12GB, rather it’s a major overhaul of the technology.
In our previous blog on SAS, we discussed about SAS 24G new encoding and features. In the series of SAS blogs, here we shed some light on other generations of SAS that are still hot in the market.
SAS follows its own version of Moore’s law, doubling the speed every few years. Keeping up with the tradition, SAS 24G (Gen-5) was recently introduced. Let’s decode, how the effective speed has been doubled to 24G, though signaling rate remains at 22.5G. This has been achieved through a more efficient 128b/150b encoding scheme to realize a usable data rate of 24G while retaining compatibility with 6G and 12G. Additional features were also introduced to improve the overall protocol efficiency. Some of the newly added features include binary primitives, primitive parameters, SMP open priority, inter-expander fairness arbitration enhancements, … etc. In this blog we will look into some of the new features, and will continue to delve into more details in the upcoming blogs on SAS.
Synopsys recently announced the availability of industry’s first VIP to support the Serial-attached SCSI (SAS) 24G standard. Let’s look back how far we have come along, let’s time travel and re-live the interesting journey of storage and SCSI evolution.
How fast do we want to access our data? There is a never ending demand for faster and better storage technologies and SAS-4 24G is the latest addition to this. SAS (Serial-attached SCSI) offers an ideal solution for applications with substantial storage, backup and archiving demands. SAS is widely considered to be the prevalent interface for direct-attached storage and is used to support hard drive controllers in enterprise-grade server farms. SAS-4 has doubled the rate with 22.5G signaling and a more efficient 128b/150b encoding scheme to realize a usable data rate of 24G while retaining compatibility with 6G and 12 G.