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I wonder if anyone can tell me typically how many spare non-LBA sectors (as a propotion of the LBA size) a HDD typically has.
I just took an 8TB Seagate drive and got these results
Code:
User Partition
LBAs 000000000000-0000756080F9
PBAs 000000000000-000076893477
System Partition
LBAs 000000000000-00000013497F
PBAs 000000000000-000000146F3F
Media Cache Partition
LBAs 000074702556-0000756080F9
PBAs 0000759486D0-000076893477
Spare pool
PBAs: 00007578F548-00007586BDF5 RST Available: 8000 SCT Available: EF
Spare pool (Multi-IOEDC Region)
PBAs: 00007687B32C-0000768872C1 RST Available: 400 SCT Available: 1A
The numbers are hexadecimal, in large (4K) sectors, it means that you'd have to multiply them by 8 to convert them to "normal" LBAs
Addressable user space in LBAs is: 15628053168
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Simple erasure tools are unable to clean these or the bad sectors that have been remapped to them but some government accredited tools (such as Blancco) can. Hence I want to try and put a theoretical absolute upper limit on the amount of data that might survive a simple erase.
There is no way to get
LBA access to the in-addressable LBAs, no matter how much "government accreditation" a tool can get.
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As a supplementary question: can I access non-LBA sectors in any way using MHDD?
no, MHDD can't access it (I'm not taking in account vendor-specific commands that theoretically can be written as scripts for MHDD)