Hard Disk Monitoring

Is it possible to just suface scan a range of sectors? I've done a Surface Scan - READ, and it found a bad sector and then a few slow spots after it. I would like to do the write-read-write to fix that spot but don't want to do the entire disk when it would be really fast just to do it to that group of sectors and be done. Any chance of that, or will I have to do the write-read-write to the entire 3tb disk?

Yes of course:

Please select Disk menu -> Surface test and select the disk drive to be tested and the test type.
Then click on the Configuration tab in this window where you can specify options for the test: enable the Limit testing to specific data blocks
and specify the First block / Last block numbers to test only partial data area. The whole surface divided to 10000 blocks, so (for example) if you specify

First block = 0
Last block = 2499

then the test will perform the first 25% of the disk drive.

However, I suspect you mean the Read - write - read test (refresh data area) test. I can confirm that this is NOT applicable to repair this kind of problem: when it finds the unreadable sector, it will ignore (not refresh) exactly to prevent possible data corruption of the affected sector.

If I'm correct, maybe weak sector(s) reported in the text description.
As you may read on Support -> Frequently Asked Questions -> Hard disk case: weak sectors
https://www.hdsentinel.com/hard_disk_ca ... ectors.php
other tests should be used in this case:

Disk menu -> Surface test -> Disk Repair
or if this is "not enough", for example the health is low and the amount of problems are high, then the
Disk menu -> Surface test -> Reinitialise Disk Surface (but this is a destructive type test which clears the data area)