[quote=debro;2236627]So effectively, if you get 1000pi errors on an 8ECC scanning drive, you can’t determine whether there is 125 PI errors per block and the disc is usable, or whether all 1000 are in a single block and the disk is useless ;)[/quote] Pretty much right - especially for PIF.
The ECMA standards specify acceptable PIE per 8 ECC blocks, while acceptable PIF are specified per 1 ECC block.
When using a 1 ECC scanning drive, the scanning software can trivially add up PIE values for 8 x 1 ECC samples at a time.
When using an 8 ECC scanning drive, the scanning software cannot know how to divide the reported sum of PIF for 8 ECC blocks into how many PIF were in each of the 8 x 1 ECC blocks, however.
This is why I call 1 ECC scanning “more fine-grained”.