Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command

[Dietmar Maurer]

> That sounds like more work than a persistent dirty bitmap.  The advantage is 
> that
> while dirty bitmaps are consumed by a single user, the Merkle tree can be used
> to sync up any number of replicas.

I also consider it safer, because you make sure the data exists (using hash 
keys like SHA1).

I am unsure how you can check if a dirty bitmap contains errors, or is out of 
date?

Also, you can compare arbitrary Merkle trees, whereas a dirty bitmap is always 
related to a single image.
(consider the user remove the latest backup from the backup target).