Speed Profile Examples - Feel free to post your own snapshots as examples for users that may not be familiar with these profiles

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The purpose of this speed profile discussion is for anybody interested to post snapshots to this discussion of nwipe's speed profile graph as found on the single disc and system multi disc certificates, as examples for users that may not be familiar with how a speed profile graph should look like on good and failing disc drives.

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Example 1

Single pass, showing typical reduction in speed as heads move to inner cyclinders. Drive has no faults, no reallocated sectors, no significant errors recorded in smart data. This is what is expected for a drive that has no faults.

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Example 2

PRNG pass + PRNG verification pass + Blanking (zero) pass + zeros verification pass, expected saw tooth graph as heads retract back to outer cylinders for each new pass. Ignore x axis label in minutes. X axis will always be percentage completion and not minutes. This is what is expected for a drive that has no faults.

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Example 3

This graph used the same method as example 2 PRNG + blanking + all pass verification. Interestingly the drive reported 0 errors and 0 retries. The drive had no reallocated sectors, however if the smart data was examined closely there was a value that seemed high, read_soft_error_rate = 77762928 and hardware_ecc_recovered 77762928. The first pass speed was normal, the average speed throughput is lower than expected. However the user could have missed the fact that this drive has a serious read problem that isn't reporting I/O errors.

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Example 4

This graph shows a failing drive that ultimately ended the wipe with I/O errors hitting the 3 retries limit. Notice the eratic speed prior to the drive ultimately failing.

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Example 5

This represents a ones method + verification on a cheap unbranded USB stick 'General UDISK' with a sustained write of about 8MB/s and read of ~23MB/s, no faults.

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Example 6

Another unexpected result on a drive that at first glance appeared to be operating normally, except for one symptom. Smart data reports the drive as good, it erases and verifies with no errors or retries, however an anomaly that is easily overlooked was the behaviour of the accumulated average throughput shown by nwipe during the wipe. It reported 61MB/S when the wipe started and 61MB/s when the wipe finished. With spinning discs you normally see a higher average at the start of the wipe and it slowly drops in throughput which is the normal behaviour. The speed profile graph gives as an insight into what is going on. Is this a fault? Or did the manufacturer throttle the write speeds?**

I'll leave you with this drop down, AI results follow so all the usual disclaimers apply.

Did Hitachi throttle the write speeds of some of their hard disks?

Yes, this occurred with several hard drives based on Hitachi (HGST) platforms after the brand was acquired by Western Digital.

Instead of manufacturing entirely separate low-speed hardware, Western Digital repurposed high-end Hitachi Ultrastar 7200 RPM enterprise hardware for their consumer-grade "5400 RPM class" drives (such as WD Red NAS and external "white label" drives).To make these 7200 RPM drives perform like slower, cheaper drives, they did two things:

• Throttled the Transfer Speeds: Their firmware deliberately capped the sequential read and write speeds (often from over 250 MB/s down to roughly 200–210 MB/s) so they wouldn't compete with more expensive 7200 RPM models.
• Faked the Reported RPM: The drive's firmware was modified to report a spindle speed of 5400 RPM to the operating system's SMART data, even though they physically spun at 7200 RPM (generating the higher heat, power draw, and noise profile of a faster drive).

Harrison, H. (2020). Western Digital admits some '5400 RPM' hard drives actually spin at 7200 RPM. Ars Technica.

• Ars Technica (September 2020): "Western Digital admits some '5400 RPM' hard drives actually spin at 7200 RPM"

  • This article details how WD used Hitachi (HGST) 7200 RPM platforms in their WD Red and external "shucked" drives, labeled them as "5400 RPM class," and used firmware to throttle the transfer speeds to match expected 5400 RPM performance.

• Reddit (/r/DataHoarder) Investigation (2020): * The issue was originally discovered and heavily documented by independent users on Reddit. Hobbyists used audio spectrum analysis (measuring the acoustic frequency of the drive's spindle hum at 120 Hz, which corresponds to 7200 RPM, rather than 90 Hz for 5400 RPM) to prove the drives were spinning faster than advertised.

• StorageReview (2020): "WD Red HDDs Spinning at 7200RPM Labeled as 5400RPM"

  • This publication verified the community's findings, confirming that the drives (derived from HGST Ultrastar designs) were physically spinning at 7200 RPM but throttled via firmware and misreported in SMART data.

(Note: Because these are technology news reports, consumer investigations, and manufacturer statements rather than peer-reviewed academic journal papers, they do not have academic APA/BibTeX metadata or DOIs.)

PRNG pass + PRNG Verification pass, 2 rounds, showing throttled? PRNG write pass, or is it a fault. PRNG pass + PRNG Verification pass + Blanking (zeros) pass + zeros verification. 1 round. Showing throttled writes on both PRNG and zeros passes.

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Example 7

160GB Samsung WDC WD1600AAJS-6. The drive has no faults. This shows the speed profile of a scatter wipe. I've also included the standard forward sequential write as a comparison, both completed on the same drive. Both wipes used the exact same method except one was scatter and one sequential. I expected the flat line for a scattered wipe, but did not predict the slight difference in read and write, that doesn't appear in the sequential write. This can be considered a normal result showing the drive behaving correctly. However the scatter read (verification) on both prng and zeros being slower than write is certainly unexpected and counter intuitive.**

160GB Samsung WDC WD1600AAJS-6: Scatter wipe, PRNG + verification + Blanking (zeros) + zeros verification.

160GB Samsung WDC WD1600AAJS-6: Sequential wipe, PRNG + verification + Blanking (zeros) + zeros verification.

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Added example 6 to speed profiles. #775