Samsung 840 White Paper page 6

02
Understanding SSD System Requirements
SATA Interface Basics
SATA is the name of the interface standard that allows a storage device, in this case an SSD, to communicate with a
host system, in this case a PC or laptop. It facilitates the functioning of all storage features, from basic input/output (or
read/write) requests to advanced AHCI-enabled features like Native Command Queuing (NCQ), hot-swapping, power
management, and RAID. SATA has gone through several revisions in its lifetime, boasting significant performance gains
with each iteration. The SATA interface generation a PC is equipped with will have a direct impact on maximum SSD
performance. For this reason, it is crucial to understand the difference between each SATA revision and the capabilities
each will afford a modern SSD.
SATA Revisions
Generation
SATA 1.0
SATA 2.0
SATA 3.0
SATA 3.1
SATA 3.2 8Gb/s & 16Gb/s (800MB/s & 1600MB/s)
SATA 1.0
Released in 2003, SATA I, also known as SATA 1.5Gb/s, is the first generation of the SATA specification. As its name implies,
it is able to communicate at up to 1.5Gb/s. This early revision does not support some modern storage features, such as
Native Command Queuing. Maximum transfer rates are around 150MB/s, slightly better than the older PATA interface (also
called UDMA 133) it replaces, which had a maximum speed of 133MB/s.
SATA 2.0
SATA 2.0, also known as SATA 3Gb/s, is the second generation of the SATA specification. Released in 2004, it is capable
of communicating at up to 300MB/s. This revision also introduces Native Command Queuing (NCQ), a feature that
improves multitasking performance. SATA 2.0 is more than capable of handling the best hard drives on the market, but
it is easily overwhelmed by the onslaught of Flash devices (SSDs) that are now popular. Computers purchased in 2005 or
later are likely equipped with SATA 2.0 support.
SATA 3.0
Released in 2009, SATA 3.0, also known as SATA 6Gb/s, is the third generation of the SATA specification. It is capable of
communicating at up to 600MB/s, with overhead taken into account. In addition to its speed improvements, this revision
also introduces NCQ management, improved power management features, and queued TRIM support (allowing TRIM
commands to be queued with I/O requests, which was not possible on earlier implementations). While it is currently
capable of supporting the massive speeds of today's SSDs, it is already being outpaced as SSD technology advances. This
is the standard that most modern SSDs are built to support, although they are backwards compatible with the earlier
standards as well.
Speed
1.5Gb (150MB/s)
3Gb (300MB/s) Native Command Queuing (NCQ) support
New NCQ Management feature, Improved
6Gb (600MB/s)
connectors to accommodate new device
6Gb (600MB/s)
Special Features
power management, support for new
form factors, queued TRIM Command
mSATA support
SATA Express support (not finalized yet)
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