WD 2TB Weak Sectors

[Kebby]

The test has been running for long time now (and rest of the graph was also dark green. I wanst able to take screen shot after the test completed). I have already read about the various colors in docs and just wanted to confirm if this is something I should worry about since there are lot of dark green block.
Is there any other test that I should run to fix it.

Thanks

[hdsentinel]

Yes, I can confirm that this is normal during write test for this type of hard disk (SMR hard disk).
Generally high amount of written data (for example a complete write test) can cause that the end of the drive seems slower than expected, resulting darker green blocks. This is caused by the data recording technique used in these drives.

Slightly similar hard disk and issue mentioned in this topic too:

https://www.hdsentinel.com/forum/viewtopic.php?p=19513

If you check a Disk menu -> Surface test -> Read test, probably there will be no such darker color which will confirm that generally the affected area is correct (I think so if the hard disk has 100% Health now, after the Disk Repair test successfully repaired the weak sectors).

[Kebby]

I did perform the read test and it was all light green as far as I can recall and thought Read Test might not be able to detect bad sectors as good as the "reinitialize disk" does since I dont have the complete understanding.
I must say the last 2 % of the test takes the longest 4-5 hours.

Thanks for the confirmation. I will look up SMR drives

[Kebby]

Btw I am curious about the possible reason for the difference between my graph vs the one your previously mentioned post. Could it be because of buffer size.
Also is there a way to know if a disk if SMR or CMR since the manufacturer doesn't mentions it on their website? Also can you pls provide more info or provide some resource which explains a bit more about the data recording technique used in these drives which you previously referred to.

Thanks

[hdsentinel]

No, sorry for the possible confusion: the "Read test" is also able to detect and reveal possible problems, so exactly this designed FIRST to detect, reveal the problems like unreadable sectors.

The "Read test" may not able to FIX them (if found), just reveals the problems - or can confirm if the drive is generally working correctly.
The Reinitialise Disk Surface test performs the FIX too.
But to DETECT, the Read test is perfect solution.

If all blocks are light green during the read test and the Disk Performance Graph does not show such drop (just the slight decrease) then everything is fine.

If you prefer, you can any time use Report menu -> Send test report to developer option, as then it is possible the actual situation.

[hdsentinel]

Yes, there are different factors: buffer size, internal firmware and its operation, possible USB controller (in case of external drive) and so.

Yes, manufacturers do not prefer to show this information at all. Usually exactly the opposite, sometimes they want to "hide" this and does not really prefer users to "know" things for sure. Different techniques (eg. adjusting the buffer size, zone size, firmware changes) used to hide this behaviour and (at least in most situations, until we perform a complete Reinitialise Disk Surface test in Hard Disk Sentinel) we may not notice this SMR-specific behaviour at all.

Please check
https://zonedstorage.io/docs/introduction/smr
which generally explains how this works. Manufacturers may implement slightly differently for each hard disk model families / models / firmware but you'll get the idea.