Re: [Qemu-devel] [PATCH 02/12] block/backup: Add mirror sync mode 'bitmap'

[Vladimir Sementsov-Ogievskiy]

20.06.2019 4:03, John Snow wrote:
> We don't need or want a new sync mode for simple differences in
> semantics.  Create a new mode simply named "BITMAP" that is designed to
> make use of the new Bitmap Sync Mode field.
> 
> Because the only bitmap mode is 'conditional', this adds no new
> functionality to the backup job (yet). The old incremental backup mode
> is maintained as a syntactic sugar for sync=bitmap, mode=conditional.
> 
> Add all of the plumbing necessary to support this new instruction.

I don't follow, why you don't want to just add bitmap-mode optional parameter
for incremental mode?

For this all looks similar to just two separate things:
1. add bitmap-mode parameter
2. rename incremental to bitmap

Why do we need [2.] ?
If we do only [1.], we'll avoid creating two similar modes, syntax sugar, a bit
of mess as it seems to me..

Hmm, about differential backups, as I understood, we call 'differential' an 
incremental
backup, but which considers difference not from latest incremental backup but 
from some
in the past.. Is it incorrect?

-- 
Best regards,
Vladimir