Sampled Write-Verify Test

Applies to: Pro, Enterprise, and Audit

Purpose

Sampled Write-Verify Test performs immediate write and readback comparison in representative regions after sanitization. It is designed to identify exposed write errors, read errors, or data mismatches without rewriting the complete device.

DriveErase Operation

  1. Records a SMART snapshot where available;
  2. Selects sample regions near the beginning, middle, and end of the logical range;
  3. Tests up to 1 GiB in each region;
  4. Writes all-zero data in 1 MiB blocks;
  5. Immediately reads each block;
  6. Compares the returned data with the expected zero pattern;
  7. Records write errors, read errors, and mismatches;
  8. Retains a bounded list of representative error offsets;
  9. Records a final SMART snapshot and health result.

Destructive nature

The test writes to the selected sample areas. It is appropriate only after sanitization or on a device whose current contents can be destroyed. Do not use it as a non-destructive diagnostic on a device containing required data.

Scope

This is a sampled test, not a complete full-device write test. Successful samples do not prove that every other logical block can be written and retained correctly.

Cache limitation

Immediate readback can be influenced by operating-system, controller, and device caching. The test does not power-cycle the device between write and read and therefore does not prove persistence across loss of power.

Appropriate use

Use this assessment when the device is being considered for reuse and representative post-sanitization write behavior is important. Combine it with a complete read scan or Full Health Assessment when policy requires broader evidence.