[pve-devel] [RFC qemu/storage/qemu-server/container/manager 00/23] backup provider API

[Dietmar Maurer]

> The biggest issue we see reported related to QEMU bitmaps is
> persistence. The lack of durability results in unpredictable backup
> behavior at scale. If a host, rack, or data center loses power, you're
> in for a full backup cycle. Even if several VMs are powered off for
> some reason, it can be a nuisance. Several storage solutions can
> generate the incremental difference bitmaps from durable sources,
> eliminating the issue.

Several storage solutions provides internal snapshots, but none of them has an API to access the dirty bitmap (please correct me if I am wrong). Or what storage solution do you talk about exactly?

Storing the dirty bitmap persistently would be relatively easy, but so far we found no way to make sure the bitmap is always up-to-date. 
We support shared storages, so multiple nodes can access and modify the data without updating the dirty bitmap, which would lead to corrupt backup images...