Product manual

60 Zeus
IOPS
3.5-Inch Fibre Channel Solid State Drive
SMART SPECIFICATION
OVERVIEW
This section provides the details of the implementation of SMART features for the SSD. SMART is
an acronym Self-Monitoring, Analysis and Reporting Technology. SMART originally began as a
specification for ATA devices. The specification has been adapted so that SCSI devices can support
some of the SMART capabilities. As this specification was originally conceived for drives based on
spinning platter technology, not all of the reporting features are relative to flash-based media drives.
For example, spinning disks may hold counters for the number of seek errors that occur, or report to
the host when the seek error counter reaches a threshold. Obviously, these features are not relevant
for a drive with flash-based media.
EVENTS
SMART allows the drive to track internal events and report problems to the host in an effort to predict
an impending failure. A drive with flash media and a SCSI host interface hold values and thresholds.
Although each of the following events has user-selectable thresholds, the drive will impose minimum
and maximum values to guard against improper use:
• Spare Sector Availability
• Read Error Correction Bits and Count
• Write Error Rate
• Erase Error Rate
• Read Error Rate
• Temperature
SPARE SECTOR AVAILABILITY
As the flash wears out, blocks that cannot be reliably erased or written are added to a grown defect
list. As this list grows, the number of spare blocks will decrease. During normal operation, the
firmware will attempt to free blocks by locating blocks that are invalid, spare, or consolidating blocks.
Normally this will increase the number of free blocks. The threshold for triggering the process of
locating more free blocks is set in the firmware. A user-selectable threshold can be specified as a
percentage of free blocks. When the grown defect list grows to the point where this threshold cannot
be reached, the spare sector availability reporting methods will be invoked.