The bench

How we test

Every drive crosses the same bench in the same order, and the numbers that come off it are the numbers on your report. Nothing is reset, rounded or reworded.

Four steps. Every drive. No exceptions.

Two of them are steps almost nobody in this trade bothers with. They are the reason a CrestDrives Grade A means something specific.

  1. Read it cold

    Health, performance, temperature and every sector count, captured with the serial in the same frame so the reading cannot be detached from the drive it describes. We wait for Hard Disk Sentinel to finish calibrating first, so nothing we record is an estimate.

  2. Read every sector

    A full-capacity surface read, end to end. It does two jobs: it exercises the whole platter rather than the few gigabytes a quick test touches, and it proves the drive actually holds the capacity printed on its label.

  3. Read it again

    The same attributes a second time, after the surface pass. The delta between the two readings is the point of the whole exercise — a drive whose reallocation count is still climbing looks perfect on one reading, and has nowhere to hide on two. Any rise and the drive is rejected outright. Almost nobody in this trade does this step.

  4. Wipe and certify

    NIST SP 800-88 Purge, with the certificate issued against the drive's serial number. Nothing belonging to the previous owner ships with the drive.

Health % is a composite Hard Disk Sentinel calculates. It is not a value stored on the drive, and any technical buyer knows that. We lead with it because it reads at a glance, and publish the raw attributes underneath because those are the ones you can check yourself.

The document

What you get with every drive

This is the report format, filled with specimen figures so you can see it before you order. The real one carries your drive's serial and its own numbers.

Drive diagnostic report

Sample — not a live certificate

Report CD-SPEC-0014
Issued Specimen

Capacity 16TB
Condition grade A Grade
Warranty 12 months
SMART result Pass

01 Drive identity

Model
Seagate Exos X18 16TB
Part number
ST16000NM000J
Serial
SAMPLE-ZR5A81QK
Interface
SATA 6Gb/s
Form factor
3.5-inch
Recording
CMR (conventional)

02 SMART readings

Reading 1 taken cold, after the tool finished calibrating. Reading 2 taken after a full-capacity surface read. The change between them is what decides the grade.

Attribute Reading 1 Reading 2 Δ
Reallocated sectors 0 0 0
Pending sectors 0 0 0
Uncorrectable sectors 0 0 0
Health 99% 99% 0
Temperature 31°C 38°C +7

03 Grade determination

  • Reallocated sectors at zero, and unchanged across both readings.
  • No pending and no uncorrectable sectors on either reading.
  • Full-capacity surface read completed without a defect.

Assigned grade A Grade

04 Bench record

  • Two Hard Disk Sentinel readings, taken either side of the surface pass.
  • SMART counters unaltered. No reset, no clear, no vendor tooling.
  • Sanitised to NIST SP 800-88 Purge, certificate issued against this serial.
  • Physical inspection: label, connectors, casing, mounting points.
  • Packed anti-static, in a foam-lined box rated for drive transit.

SMART evidences a drive's present health and its workload history. It does not predict the moment of failure, and nothing does. Data you cannot afford to lose belongs in more than one place, whatever the grade on this report.

Specimen document · CD-SPEC-0014 · describes no physical drive

The document above is a specimen. Its figures are illustrative and its serial number is reserved for samples — it describes no physical drive and is not a certificate for any unit we have sold. Every drive we ship carries its own report, generated from that drive's own readings and issued against its own serial.

The tool

We test on Hard Disk Sentinel. It was chosen for two reasons: it reads SAS and SCSI devices as well as SATA, including drives sitting behind RAID and HBA controllers where consumer tools go blind; and it produces a single buyer-legible health figure alongside the raw SMART attributes rather than instead of them.

What we record

Every drive is read on the bench before it is listed. The reading is taken after Hard Disk Sentinel has finished calibrating, so every figure we record is a measured value, not an estimate.

What we keep against each serial: health percentage, performance, power cycles, temperature, and the reallocated, pending and uncorrectable sector counts. That reading is the baseline a warranty claim is measured against, and you can ask us for the figures on your drive at any point, before or after buying.

Check it yourself

Health percentage is a proprietary composite that Hard Disk Sentinel calculates. It is not a value stored on the drive, and any technical buyer knows that. The counts underneath it are the numbers you can verify the moment the drive arrives. Run CrystalDiskInfo on it and compare against what we recorded.

What we will not do

  • We do not reset SMART data.
  • We do not relist a rejected drive at a lower grade.
  • We do not quote a manufacturer's new-drive annualised failure rate as though it describes a used unit. It does not.