I am building a NAS/home server, so I bought new WD Red Pro hard drives (18 TB), and the store didn't package them very well during shipment, so I decided to test the Hard Drives for bad sectors. They are empty, so data recovery wasn't important, but the speed of the test was - I wanted the fastest way to mark bad sectors/blocks of the hard drive.

This answer recommended Easeus Partition Manager with its Surface Test feature as the fastest way to mark bad blocks/sectors without recovery.

Before I ran the surface test, I tested the speed of my disks with Crystal Mark: around 200 MB/s for continuous write and around the same for continuous read.

When I started the surface test, Easeus Partition Manager displayed 10,000-12,000 MB/minute as the surface test speed. Now, the confusing part for me is that I was under the impression that the process of surface test is a 2-step process:

  1. Attempting to write to the disk sector
  2. Attempting to read the written data from that sector

12000 MB/minute of the test is the same as 200 MB/s when converted to the per second value. This should be exactly the speed of write or read alone, but not both. Isn't it the case that having to both read and write should yield half of that surface test speed = 6000 MB/s? And if so, does it mean that Easeus Partition Manager only writes or only reads, instead of doing both, to surface test a hard drive, and then how reliable is their test process? I.e., if the test says (after completing in 30 hours) that I have 0 bad blocks, do I really have no bad blocks?

P.S. I connected these internal drives externally and ran the test using a SATA to USB 3.0 adapter--if that matters.

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    You do know you will see significant speed performance drops, due to the speed differences, between SATA and USB 3.2 Gen 1?
    – Ramhound
    Commented Jun 13, 2022 at 19:31
  • That's not the question. I am not claiming that something is too slow and asking "why". I am asking why the surface test seems to be TOO FAST. It doesn't seem to spend enough time on each sector to BOTH write to and read from it. Is it doing just one of those operations as part of the surface test process? And if so, is that really enough? Commented Jun 13, 2022 at 19:35
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    I am not sure anyone outside of Easeus can answer this question since what the surface test does exactly is locked behind whatever information the UI displays.
    – Ramhound
    Commented Jun 13, 2022 at 19:38
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    On 18 TB disk - yes. I mean, I showed the math behind my suspicion - if the drive writes AND reads to a sector as part of the test, and the speed of write is 200 MBs, it should perform the test at most at 6,000 MB/minute, and yet it was testing at 12,000 MB/minute as if it wasn't both writing AND reading, but doing ONLY ONE of those things (unless it can simultaneously do write and read BOTH at 200 MBs simultaneously, but AFAIK that's not how drives work). Commented Jun 13, 2022 at 21:13
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    SMART reports zero bad sectors in Crystal Info. I didn't drop the drives, but I don't know if they got dropped during shipment. BH Photo didn't package them well. THat's why I am checking these drives in the first place. Commented Jun 14, 2022 at 19:42


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