Judging on the hours vs flying hours I'm guessing this is an external backup drive.
The ones to watch are:
Reallocated_Sector_Ct (IMPORTANT)
Reported_Uncorrected sector count (IMPORTANT)
Current_Pending_Sector (concern, as these are recoverable, though it may need a format to do so and failure to do so automatically is a bad sign)
Ignore the data, look at the raw values, everything else is interpretive and may be wrong unless you use the manufacturers software to read them, if these are ANYTHING but zero in raw data, get worried. In this case, all are zero, which is good, it means there was nothing to write and therefore not open to interpretation. No news is good news...
What is worrisome though is the error rates (seek, read and ECC recovered numbers).
These usually are not indicative of a failing platter but instead a bad cable, be it SATA or USB or a failing buffer. It's almost always the cable. The good thing with this type of error is can can monitor it after a cable change and see how your change effected it and see if things are better or not. Try a new cable and perform some large file transfers to and from using MD5 hashes to verify data integrity. Use large, freshly downloaded and verified files (linux ISOs work) starting from your computer to this drive, and back. If the MD5 checks out after a few large moves back and forth you're probably good to go.
Something to note. Even if you replace the cable and it checks out with md5 hash checks, the number may continue to rise fast on some of these because the data on the drive itself may already be compromised so those numbers are now questionable unless you copy everything off, format and put it all back then take note of the new numbers. This also won't fix any data corruption that has already happened but does clean up the errors in the files. Some files may even need to be opened and re-saved to correct them, missing data or not. If all this sounds like a pain in the neck, it is.
Remember none of this is 100%, it could fail tomorrow or last a darn long time, but in terms of what we can see it seems healthy at least firmware side.
If it was slow to boot and making any odd sounds, especially clicking, START BACKING UP NOW. These are signs of a mechanical failure in progress. Do not let it sleep, do not shut down, start backing up because the next time it power cycles or even accesses data may be the last time it ever reads that sector or spins up again. By the way, backup your windows key at the same time if you can but focus on personal data first then work out to less important stuff.
By the way under normal use desktop spinner drives have about a 50-75% failure rate by end of year 4 (Caviar Black is the exception, those get an extra 1-2 years), it being 3 years old is not a good sign. The numbers for failure start really high for year one, then drops really low for year two, then during year 3 they start ramping up. A 4 year old spinner is usually ready for retirement and if you find 7 or 8 year old one that has been in constant operation it's like meeting a 100 year old person.
Do not put any serious load, including a virus scan on a drive 4 or more years old without making a backup first, and note that backup process may kill it before the scan does. Doing a full backup or virus scan is the hardest a drive usually works for most people so it's a high risk operation. I've had numerous drives on customer systems fail this way.
