Low-Level Formatting: What is it and what does it do?

Low-level formatting (LLF) is also called "physical formatting", since it bypasses the logical filesystem layer and directly writes data onto the storage medium. LLF will erase every bit of information on a disk with data and it is nearly impossible to recover data from low-level formatted storage medium. So be advised to use LLF with caution.

What exactly does LLF do to a disk?

1. Zero-fill. High-level formatting just erase data on address table, leaving all files untouched in their raw form, which is a series of zeros and ones. Whereas low-level formatting will bypass filesystem layer and write zeros onto the storage medium, leaving no trace of previously stored data. LLF also resets ECC to prevent ECC Error.


2. Automatic Reallocate Sector. LLF will perform read/write check on each sector. When bad sectors are detected, LLF will call Automatic Reallocate Sector function to attempt  repair.

3. Re-assign Sector/track ID. LLF will re-assign Sector/track ID according to P-List and TS records. Bad sectors or defect tracks that can't be repaired will be shielded to avoid error.

4. Writing Status Report. Some HDD has the ability to monitor LLF process. If anything goes wrong during LLF, it would refuse to read/write to protect itself from further damage.

Low-level formatting is irreversible and can cause permanent data loss. Unless you intentionally want to erase sensitive information, it is not recommended as a routine practice.

Tips from data recovery experts

1. Precaution. No company or institution can guarantee 100% data recovery. Many cases of data loss are permanent. It could be physical damage, or data been overwritten. So it is crucial to take precautions. For example, always keep your storage devices in a dry and clean environment; regularly backup important data; no sudden voltage fluctuation.

2. Immediate response. Whether you turn to professional data recovery services for help or try one of those data recovery software, the sooner you act the more successful your recovery would go.

3. Caution.You can recover minor data loss by using recovery software. But be cautious when it comes to severe physical problems. Inappropriate operation may lead to further data damage. It is recommended to seek professional services for suggestion and solution.