Question about the consistency operations in cowbtree backend about dmdedup3.19 HOT 2 OPEN

Hi Oliver,

Dm-dedup core logic needs a key-value store like API to store its metadata (e.g., hash index and mapping). So, dm-btree was a logical choice because it provides a key-value API. Furthermore, dmdedup needs some transactional and consistency guarantees from its baceknds. And dm-btree provides these guarantees using dm-transaction-manager.

One could surely design a dm-dedup backend that uses dm-transaction-manager directly. But then the key-value store has to be implemented by the backend itself (e.g., like a table in DTD or anything else).

Best,
Vasily

from dmdedup3.19.

Hi Vasily,

Do you mean that we have to use the dm-transaction-manager to keep the IO shadowing feature of the cowbtree? As I understand, the last step, or the "commit" step of the cowbtree must be atomic to keep the consistency, so the dm-transaction-manager is used for that, right?

Yours,
Oliver

from dmdedup3.19.