hddgorilla wrote:
oh, so the delay of a sector depends on the contents of that sector?
For example, if you write 000000000 to that sector, or 111111111 to that sector, you get different delay? very interesting, but still, I would like to know the delay and adress of the slows sectors.
Yes, because the delays comes from the drive's error correcting methodes.
Like ECC calculating, reading-retry in the next rotation, trying to seek off and back (reposition), trying to read a little off-track, etc...
This is done if the readed content have at least 1 bit difference!
But in this way, if the address marks, sector IDs, servos are not damaged, the delays depends only in content.
hddgorilla wrote:
I normally fill my big drives with data (video or music) and then I let them stay without content modifications for years. So I think the slow sectors will always be the same (more or less) and I will be able to keep track of the evolution.
Not true, because the bit-difference can be come from the superparamagnetic effect as well, wich can be happened when the drive is offline...
hddgorilla wrote:
>>>
Additionally, if the content doesn't change, the error type not change, the surface and the head condition can be changed too with the time....
<<<
yes, precisely, I want to keep track of things like the evolution of the surface and head condition, that is, the physical condition of the drive.
Trust me, instead of drives.

I have seen a lot of times, one really good condition drive is left for some year, and after the owner turned up, the head is crashed unexpectedly.
This is the most strangest thing wich can happened. (caused by the surface's coating layer)
For drive condition tracking, there is the SMART table inside the drive.
This is the best way to track the rarely used drives, but yes, you need to read the entire drive on every power-up, for check the condition again.
If you want to store big data wich not changing, the best what you can do is build up one software raid for storing.
I prefer to use Linux, because for example in RAID4/5/6 if one sector is unreadable, the code is automatically corrected by writing again from the redundancy calculated content.

Additionally, You can better track a 365 day online drive than the rarely used!
Regards,
Janos