Any storage peripheral that does not employ any method of buffering between the storage medium and the system interface will suffer in terms of poor I/O performance. E-Disk^® and E-Disk^® Altima solid state drives employ a small amount of DRAM to serve as high-speed cache for implementing its write policies.

Given the volatile nature of DRAM, BiTMICRO^® developed DataSentinel to maintain standards of high performance without necessarily compromising data integrity. To reduce risk of data loss during low voltage and brownout situations, DataSentinel provides the following standard and user-programmable functions:

Low Voltage Detection

All writes to the peripheral are halted before the voltage drops below critical thresholds. This reduces the risk of data corruption to file allocation (FAT) or translation tables in the event of an aborted write operation. Peripherals that do not have any low voltage detection logic are more exposed to data corruption because device writes are allowed to continue during low voltage conditions.

Redundant Pre-Write

The E-Disk^® allocates a number of reserved memory blocks for use as a scratchpad and for internal translation tables. This BiTMICRO^® Networks proprietary feature pre-writes modifications to the translation tables to the scratchpad area.

Concurrent-Multiple Write

This feature reduces the risk of data and FAT corruption due to low voltage writes by reducing the "window of vulnerability" or window of time that the Flash device spends in the write phase.

User-Programmable Write-Through Cache Delay Timer

Reduces the chance of data loss or corruption when the write programmable delay is set to a very low number, at the expense of roughly 20% write performance loss. Read performance is not affected.

User-Programmable Flash Cache Size

Minimizes data loss during unexpected power failure by reducing the size of the write dirty cache to at least one sector or block of data for the controller to write.

Cache-on-Write Disable

When the user disables Cache-on-Write mode, data integrity is guaranteed because it is written directly to Flash memory before sending a positive acknowledgment to the host. There is however a severe penalty in write performance when selecting this mode. Read performance is not affected since read cycles still see the full cache size.

DataSentinel is a value-added feature in all E-Disks^®.

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