SSD endurance: Death by petabyte

In an endurance test six consumer-grade SSDs have been written to continuously until failure. The good news: They all exceeded their endurance specs by a substantial margin. But half have failed before reaching a petabyte of writes.
Written by Robin Harris on

The good folks at The Tech Report have subjected SSDs from Corsair, Intel, Samsung, and Kingston to a write-until-failure test to see how long they last and how they fail. If you are professionally interested read the entire piece. But here are the high points.

While all the drives handled over 700TB of writes - far more than they'd see in normal use - three failed before reaching 1PB. A Kingston HyperX 3K died at 728TB, while an Intel 335 reached 750TB.

The Samsung 840 250GB - using three-level cells that have lower endurance than MLC - was the next to fail at over 900TB.

Dance of death  Most drives all warned of imminent failure - giving enough time to back up data - but then had different behaviors. 

The Intel media wearout indicator (MWI), available through the SMART interface, showed the drive was done. At that point the drive is supposed to go into a read-only state, but after more writes and a reboot the drive was detected as a 0GB SATA drive.

There were two HyperX 3K SSDs, one writing incompressible data while the other got compressible data to test the controller's DuraWrite technology. DuraWrite does inline compression and full block writes to reduce wear.

The incompressible HyperX died after several warnings, and then bricked after a reboot. It appeared the HyperX died after using all the available flash.

The Samsung 840, whose TLC flash has roughly a tenth the endurance of MLC, started bad block replacement at only 200TB. At 300TB it began showing uncorrectable errors, causing it to fail some tests. But it still worked at 900TB before dying without any SMART warnings.

The Samsung 840 Pro with MLC has kept working beyond 1PB, but it isn't clear what the failure mode will look like. The Corsair and the other Kingston also carry on.

What does this mean to you?  If you are creating or editing spreadsheets, documents and presentations, you'd have to be pretty busy to update even a gigabyte per day, or a terabyte every 2-3 years.

If you are editing video or music you might write 100GB a day, or a TB every 10 days, and it would take you over 13 years to reach 500TB. Bottom line: all these drives have plenty of endurance for consumer uses.

The Storage Bits take  These are encouraging results. The drives comfortably exceeded their endurance specs, addressing a major concern that many sysadmins have had with SSDs.

The differing failure modes suggest that larger shops will be happier buying one brand whose behavior they can learn, rather than buying on price. While most workloads aren't going to ever write a petabyte, there are other factors - such as multiple die failures - that could cause some drives to fail sooner than expected.

Given that these SSDs are all consumer-grade, their endurance is remarkable. But there are reasons other than media wear out for SSDs to fail, so back them up just as you would a hard drive.

Comments welcome, as always.  Have you had any media wear out on your SSDs?



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