| BiTMICRO Knowledge Base |
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fq040524-03 - How Does the E-Disk® Drive Manage Defects that Develop in its Flash Memory Chips? 
QUESTION: How does the E-Disk® manage defects that develop in its flash memory chips? ANSWER: Due to normal wear and tear, there will always be a possibility that the E-Disk® flash drive will encounter bad memory blocks as flash memory approaches its write/erase cycle endurance limit. When the number of correctable errors for that block reaches a user configurable threshold value, remapping is performed by firmware on-the-fly to replace logical block address entries that point to bad blocks with new good blocks. The E-Disk® flash drive ships with a reserved number of flash memory blocks for this purpose. The amount of reserved memory blocks varies from 1% to 2% depending on the capacity. For capacities greater than 10 GB, it is 1%. For E-Disk drives with a capacity of less than 10 GB, reserved blocks is 2%. Before the reserved blocks of memory are used up, the red LED will start flashing to provide a visual alert to the user that there are only a few reserved blocks left and that the flash drive should be replaced soon. The E-Disk® flash drive will continue to function in this situation. RELATED LINK(S):  E-Disk® Features: Self-Healing Diagnostics and Maintenance
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