SSD Total Bytes Written Calculator

Solid-State-Drives are getting more and more common. A problem that comes with SSDs is their limited cell lifetime. Depending on their manufacturing technique, each cell can be overwritten from 1.000 times in consumer TLC SSDs to up to 100.000 times in enterprise SLC based SSDs.

The value to keep an eye on is the guaranteed TBW (Total Bytes Written or Terabytes Written) which is typically provided by the vendor in their specifications. This value describes how many Terabytes can be written to the device until the warranty expires. The TBW value can be readout with S.M.A.R.T. in the Total_LBAs_Written field. The value is in LBAs which has to be multiplied with the sector size:

On common Linux Systems you can determine "Total LBAs Written" and "Sector Size" with smartctl:

~# smartctl /dev/ada0 --all |grep "Sector Size"
Sector Size: 512 bytes logical/physical
~# smartctl /dev/ada0 --all | grep Total_LBAs_Written
241 Total_LBAs_Written 0x0032 099 099 000 Old_age Always - 25351376107

Smartctl is not available on ESXi hosts by default, but the Linux compatible precompiled versions should work with ESXi (use the latest x86_64 build). Just copy it to your ESXi host, make it executable and run it as explained here.

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