SSD (Formerly FFD) Ultra ATA 2.5"
30
Product Specification and User Manual
41-PS-0104-00 Rev. 2.3
4.6.5.
S.M.A.R.T Command
In an effort to help users to avoid data loss, mechanical disk manufacturers incorporate logic into
their drives that acts as an early warning system. This system is called Self-Monitoring Analysis
and Reporting Technology, or S.M.A.R.T. The hard disk‟s integrated controller works with
sensors to monitor various aspects of the drive‟s performance, and determines from this
information whether or not the drive is behaving normally and reports its status. The
fundamental principle behind S.M.A.R.T. is that many problems within mechanical hard disks
do not occur suddenly, but result from a slow degradation of various mechanical components.
Mechanical characteristics commonly analyzed by the S.M.A.R.T. command are head-flying
height, number of remapped sectors, spin-up time, drive temperature and data throughput.
S.M.A.R.T implementation in the SSD takes an alternate approach. As the SSD is a solid-state
disk with no moving parts, there is no point in testing SSD mechanical functionality. The
S.M.A.R.T. command in the SSD analyzes the number of bad blocks that were accumulated in
the SSD relative to the total amount of spare blocks.
When the flash media returns a failure at a block, the data from that block is transferred to a
spare block (transparently to the host), and the failed block is marked as bad. The number of
spare blocks on the media is close to 4%, which provides balance between cost and reliability.
When the S.M.A.R.T. command is executed, subcommand is RETURN STATUS and the SSD
calculates the following parameters:
The total number of spare blocks reserved at the time the SSD was shipped from the factory.
The current number of spare blocks available on the SSD.
For the S.M.A.R.T. command, the subcommand RETURN STATUS returns one of two possible
statuses:
Passed
: If less than 95% of the total reserved spare blocks at the time of shipment were
already used.
Failed
: If more than 95% of the total reserved spare blocks at the time of shipment were
already used
The S.M.A.R.T remote monitoring analysis can be used as a trigger for disk alarm and for
immediate preventative maintenance, namely to replace the SSD before it passes into read-only
mode.
