Solid-state storage UBER (unrecoverable bit error rate) is the percentage of bits that have errors relative to the total number of bits that have been read.
To determine a storage media’s UBER, the vendor does extensive testing and uses the following mathematical formula:
UBER= number of data errors/number of bits read
UBER is a traditional measurement for mechanical hard drives, but its application in solid-state storage must take into consideration the unique qualities of the media. In JDEC endurance testing, for instance, the UBER values for SSDs are lifetime values for the sample of solid state drives being assessed and a sector containing corrupted data is counted as one data error, even if it is read multiple times and each fails to return correct data each time.