Hello, A pending Sector is usually the result of a piece of corrupted data on the sector. Viruses, Malware can cause these to some degree. since your drive is a Western Digital I can help you , In these cases the sectors do repair themselves.
Entirely wrong (or perhaps worded in a fashion that is very easy to misinterpret).
Data can be corrupted in quite a few ways that have nothing to do with hardware; for example a bug in a piece of software could cause it to write data to a file in an incorrect manner ('incorrect' being incompatible with whatever format that file type is normally expected to be written in), which causes the software problems the next time it tries to read data from that file. Sectors do not get marked as bad because of corrupted data, they get marked as bad because the sector cannot be read normally (which the OS may consider to be 'corrupted data' when a read request fails). No software I'm aware of can cause bad sectors (unless maybe it's somehow allowed direct access to the drive head - which I'm not sure is even possible). Sectors cannot repair themselves; If the HDD spots a bad sector, it will try and recover data from that sector, copy it to another sector, then mark the sector as bad / not to be used again.
A 'pending sector' is one that has been spotted as 'bad' but the drive hasn't gone through the full routine of trying to recover data from it and mark it as bad / not to be used again.
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As for the situation of 'what to do about this possibly iffy HDD' is up to you. One universal piece of advice is always:
Make sure your valuable data is backed up onto another storage device.
After that, would this drive failing be a real inconvenience to you or just an irritation? Consider how long it would take you to get a replacement drive and any work required to replace the old with the new.
If it's just an irritation, then you might want to wait for if/when the drive starts presenting you with more problems.
If it would be a real inconvenience if the drive failed unexpectedly, then I would advise replacing it ASAP before that happens.
For my own computer, I ran a Seagate drive for a fair few months after I spotted iffy SMART readings (which weren't the result of problems I noticed, just a routine check). I eventually replaced the drive because it was having problems resuming from hibernation (which disappeared after I did a full chkdsk, so the bad sectors were spotted and added to Windows's bad sector list and so weren't used again).