Serial ATA Flash Drive

APS25M5Axxxx-AXX

9

© 2011 Apacer Technology Inc.

Rev. 1.0

3.6

S.M.A.R.T.

S.M.A.R.T. is an acronym for Self-Monitoring, Analysis and Reporting Technology, an open standard allowing

disk drives to automatically monitor their own health and report potential problems. It protects the user from

unscheduled downtime by monitoring and storing critical drive performance and calibration parameters. Ideally,

this should allow taking proactive actions to prevent impending drive failure.

Apacer SAFD25M4 uses the standard SMART command B0h to read data from the drive for SMART feature

as the SATA Rev.2.6 ATA/ATAPI-7 specifications. Based on the SFF-8035i Rev. 2.0 specifications, Apacer

SMART defines vendor-specified SMART Attribute IDs (A0h, A1h, A2h, A3h, A4h-A5h) in SAFD25M4. They

represent initial back block count, bad block count, spare block count, maximum erase count, and average

erase counts respectively. When the Apacer SMART Utility running on the host, it analyzes and reports the

disk status to the host before SAFD25M4 is in critical condition.

3.7

TRIM

Made of millions of NAND flash cells, SSD can be written into groups called pages in 4K size generally, but

can only be erased in larger groups called blocks of 128 pages or 512KB. These stipulations are partially the

source of many performance issues. Until an address gets used again, the SSD has to keep track of every

last bit of data that’s written on it. The ATA-TRIM instruction tilts the balance in favor of the SSD. TRIM

addresses a major part of the performance degradation issue over time that plagues all SSDs. A TRIM

enabled drive running an OS with TRIM support will stay closer to its peak performance over time.