AVAMAR : Phases of hfscheck

The phases of hfscheck you mentioned above run in the following sequence:

1. indexsweep
2. datasweep
3. paritysweep
4. refcheck

During the indexsweep phase, the system confirms the integrity of the index (the index is the "table of contents" for all the data on the system) and also caches the index entries for each data chunk onto the same disk where the chunk itself is stored. This is done to improve the performance of later phases of the hfscheck.

The datasweep phase is typically the longest phase of hfscheck. This phase reads each data chunk from the system and compares the hash of that chunk with the hash that is recorded in the index. This confirms that each data chunk is the same as it was when it was backed up.

As I'm sure you know, multi-node Avamar systems are protected by RAIN parity. During the paritysweep phase, the parity information is recalculated and checked against the parity information on disk.

The refcheck phase of hfscheck checks the referential integrity of the backups by verifying that every chunk of data that is referenced by a backup can be found in the index.

If you find anything unclear about the explanation above, please don't hesitate to reply with questions.