SSD Reliability In The Real World

Solid-State Drives Tested

Using data from millions of drive days in Google datacenters, a new paper offers production lifecycle data on SSD reliability. Surprise! SSDs fail differently than disks – and in a dangerous way. Here’s what you need to know.

Key conclusions

  • Ignore Uncorrectable Bit Error Rate (UBER) specs. A meaningless number.
  • Good news: Raw Bit Error Rate (RBER) increases slower than expected from wearout and is not correlated with UBER or other failures.
  • High-end SLC drives are no more reliable that MLC drives.
  • Bad news: SSDs fail at a lower rate than disks, but UBER rate is higher (see below for what this means).
  • SSD age, not usage, affects reliability.
  • Bad blocks in new SSDs are common, and drives with a large number of bad blocks are much more likely to lose hundreds of other blocks, most likely due to die or chip failure.
  • 30-80 percent of SSDs develop at least one bad block and 2-7 percent develop at least one bad chip in the first four years of deployment.

Source:
SSD reliability in the real world: Google’s experience | ZDNet

See also:
The SSD Endurance Experiment: They’re all dead – The Tech Report

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