What is inside the system partition of the hard drive?

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Dec-25,2025

What is inside the system partition of the hard drive?

System area information classification:

1. SMART data
2. System logs
3. Serial number
4. Model information
5. P-list (Primary defect list - manufacturing defect information, unchanged)
6. G-list (Growth defect list - sector relocation table)
7. Program coverage - firmware, executable code, or updates
8. Area table
9. Servo parameters
10. Specific tables, such as RRO - (Repeatability Runout Calibration and Head Offset)
11. Test routines
12. Factory default tables
13. Recalibration code routines
14. Converter data:
    a. Conversion of logical and physical addresses to positions on the drive
    b. Head and track offset information
15. Drive security data password - may contain encrypted information.


   System area or system information description:

  • Usually, there are two or more copies on different drive disks

  • In most cases, system information is located on the outer track - the outermost edge

  • If the information is damaged, you can copy from the second copy to make the drive operational

  • System log information can be written here

  • System area - There is no unified or standard approach

  • Each drive and each drive series are completely different

  • Sometimes, special tools can be used to copy from similar drives or drive families

  • The smaller the amount of data stored in the system area, the greater the likelihood of replacing it with spare parts, printed circuit boards, and magnetic heads.

The system area is composed of UBA (Utility Block Addressing) modules, which are logically grouped sector blocks containing specific modules. Each UBA block may vary depending on the drive manufacturer. UBA may represent SMART data on one drive and different types of data on another drive. The UBA area is not accessible through standard interfaces. Most commands for communicating with UBA modules are vendor-specific and are usually not publicly available.
Most people are aware that their hard drives have a bad block table. However, what most people don't know is that their drives possess two bad block tables.
1. P-list (Primary Defect List - manufacturing defect information, unchanged)
2. G-list (Growth Defect List - sector relocation table) The G-list is where bad blocks that occur daily on the storage drive are stored.
Since the P-list is completed during manufacturing, this list should never be changed. Understanding these two lists is crucial for low-level recovery.
Below is a brief explanation of what may cause a "clicking sound" during startup.

Another reason for the "clicking sound" is physical sector damage.


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