CHKDSK vs Seagate diagnostic tools

[cafed00d]

cafed00d: However, if either tool comes across a bad sector, the hardware in the hard drive will automatically move the bad sector to a new location.
bbearran: Not quite. A sector is a physical location on the hard drive. Sectors aren't moved. ... It marks a bad sector as unusable and allocates a different, usable sector.
cafed00d: Which is, of course, what I meant. I apologize for not being technically accurate.

I have been rethinking my retraction. When I was having problems with Seagate drives (all 3 of them failed and had to be replaced) I was reading some of the documentation that Seagate provided (if I can ever find it again I will provide a link or a quote). In modern disk drives, you do not have access to all of the sectors. There is a small pool of sectors that is held in reserve. The firmware on the hard drive constantly monitors the state of each sector and if it comes across a bad sector it will automatically remap the sector to one of sectors in the pool. It does this behind the back of the OS and any apps that the OS is running. And as far as the OS is concerned, that sector is still in the original location.

When you run chkdsk and it validates the file and directory structure, if it comes across a bad sector, the firmware in the hard drive will remap the bad sector to the pool. Provided that the data from the bad sector can be moved to the good sector in the pool, chckdsk won't even know that anything is wrong. However, it is very possible that a good sector (according to the hard drive) can have bad data (according to chkdsk), in which case chckdsk will fix it as best it can.

[DavidPierson]

Would you still recommend changing the drive?

Install Hard Disk Sentinel from www.hdsentinel.com and in the S.MA.R.T. tab, check the following rows:
Reallocated Sector Count
Current Pending Sector Count
Off-line Uncorrectable Sector Count

Oh yeah, first right-click on a row, and in the pop-up menu, select "Decimal data fields" - not sure why it defaults to hexadecimal on install.

There is a lot of data shown which can be overwhelming at first, but the overview is this:
- the "Data" field shows the value that makes sense to us, i.e. you prefer zero for those rows I mentioned.
- the "Value", "Threshhold" and "Worst" are all scaled (usually 100 to 0, or 250 to 0) starting out with 100 being perfect and as events happen the "Value" will decrease. If they go down to "Threshold", its a warranty event.
- should be all green ticks in the first column.

It's a great program, it's free, but you can pay to register if you like it.