PRELIMINARY/CONFIDENTIAL
6
MACH2 2.5-Inch Serial ATA Solid State Drive
Bad-Block Management
The bad-block mapping algorithm replaces bad-blocks with new ones from available spares. Two
percent (2%) of the flash memory is held in reserve (spare blocks) for bad block replacement. Bad
blocks in the media are flagged when detected. When an attempt is made to access a flagged block,
the selected spare block is substituted. The bad-block mapping function enables data to be
automatically transferred from a bad sector to an available spare block.
Data Retention
Data stored on the SSD remains valid for 10 years without requiring power support. The unit can be
stored under certain environmental conditions for extended periods without any occurrence of data
degradation.
Error Detection and Error Correction
The Error Detection Code and Error Correcting Code (EDC/ECC) helps maintain data integrity by
allowing single or multiple bit corrections to the data stored in the flash array. If the data in the flash
array is corrupted due to aging or during the programming process, EDC/ECC will compensate for
the errors to ensure the delivery of accurate data to the host computer. The EDC/ECC engine is
capable of correcting up to 2 bytes in error and detecting up to 3 bytes in error. An extensive retry
algorithm is also implemented on the SSD, so that single event disturbances such as ESD or EMF
occurring during a read operation can be readily overcome.
Reliability
The following factors affect the reliability statistics of the SSD:
•
DC power is maintained as specified in this document
•
Errors caused by the host are excluded from the rates
•
Errors from the same causes are counted as 1 block
•
Data stream is assumed random
The drive is scanned for bad blocks during the initialization of
the flash components. An initial bad block table is created
from these identified marked bad blocks and any bad blocks
discovered during the testing process.
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