I think his is complicated.
I recently got 2 HDD for mass backing up. With the first I first ran a diagnostic which ID'd bad sectors and then offered to 'get rid of them' which it then claimed to have done once I clicked OK (FAT32). Knowing bad blocks were about I went to read up. I read the best way to reallocate (sparing) of bad blocks is to force the drive to reallocate bad blocks by using the write zeros feature. So I continued with that. 16 Hours later it finished.
The second drive I went straight to the Write Zeros test but this time noticed a warning that it would completely delete all data on the disk..partitions and file system data (IE my first test on the other drive went down the tubes..and took 11 hours). Then this got me thinking more...if I do a Write Zero test then all the bad sector data will be in one system volume (since all partitions are deleted I will be left with a single partition - unallocated or not). So If I then subsequently Partition that 'single unit'..will the bad sector data be divided up and reapplied to the pertinent blocks now in different partitions or do I need to check for bad blocks again which would be difficult as the Write Zeros would delete everything again. Bump. Come full circle. Write Zeros - Partition - Write Zeros - Partition.
I want to make these drives a s perfect as I can. Afterall the data going on them will be 'years worths' tho I am peeved they have bad blocks already, but I'll put that down to getting them from Comet rater than a PC specialist which treat HDD with respect.
Lots of this is new to me so maybeez its a woods and trees thing at the mo.