How many bad blocks in a HDD is too many?

Question

I am at my second attempt to get a brand new undamaged HDD (the first attempt yielded a question already) but I am starting to lose hope. The new drive I got is S.M.A.R.T. healthy but has a lot of bad block. It has exactly 1GB worth of bad block every 1TB and I am starting to thing I would have found just as many bad blocks on the previous drive if I had done a thorough write test.

Unfortunately for the second drive; the computer crashed before I could finish to check the entire drive but when HDDScan wrote 2.7TB to the drive it found exactly 2.7GB worth of bad block (thorough write test). I am starting to think that HDDScan is non sense. (just so you know and like I said in my previous superuser question I did a Seatools Long generic test (which is a long generic read on the drive) on the first drive and Seatools found nothing. I am pretty sure If I do the same with the new drive Seatools will still say the drive is OK.

Also something I haven't mention in the previous question is the fact that I had successfully filled the previous drive with data (8 TB worth of the same file and some smaller files to fill the entire 8 TB HDD) and then I tried and successfully was able to delete every files (It took 2 minutes or less I don't recall but it was fast enough). So maybe the drive was fine.

I haven't filled this new drive with a bunch of files but I am doing it now. Then I will delete every single file. My questions are:

• Is entirely filling and HDD then successfully deleting every single file, good enough to check the drive's physical health?
• Is HDDScan telling the truth really? and if not is there a better and faster alternative for a thorough write test (HDDScan took 4-5 days to write 2.7TB when it take less time to fill the entire drive with a bunch of 1GB files)?
• Is there such a thing as a drive with zero bad blocks when doing a write test (according to HDDScan or a better alternative)?
• If there is not such a drive, then how many bad blocks is too many?

EDIT: Also I am on windows 8.1 if that helps.

Answer 1

Is entirely filling and HDD then successfully deleting every single file, good enough to check the drive's physical health?

No, it is not.

Even if you 100% filled a disk with files, you wouldn't be writing to every sector because SECTORS are grouped into BLOCKS and your files are not likely going to fill each BLOCK 100%. You would have to write to EVERY SECTOR on the disk, and then try reading that sector. There are utilities for this (I assume HDDScan is one).

Unless you're using some kind of a wipe utility, when you delete a file you are just deleting the "pointer" to the file.

https://en.wikipedia.org/wiki/Disk_sector

Is HDDScan telling the truth really? and if not is there a better and faster alternative for a thorough write test (HDDScan took 4-5 days to write 2.7TB when it take less time to fill the entire drive with a bunch of 1GB files)?

Your tool likely wrote, read and verified each sector several times. The Hard Drive is one of the slowest parts of your system and 2.7TB is huge; this takes time. Your tool may offer a 'quick' option that may only do a single read/write/verify.

Is there such a thing as a drive with zero bad blocks when doing a write test (according to HDDScan or a better alternative)?

Out of the box, your new drive is unlikely to show any bad sectors because they would have been pre-flagged by the manufacturer. (someone will correct me on this)

If there is not such a drive, then how many bad blocks is too many?

What you need to be aware of is an increase in bad sectors. If you're getting new bad sectors every week (or even every month) I'd suggest replacing the drive.

I believe all drives now-a-days automatically detect and mark bad sectors. (Someone will correct me on this)