[dm-devel] [PATCH] announcing the dm-update target

[Mikulas Patocka]

On Tue, 23 Nov 2021, Akilesh Kailash wrote:

> With OTA, it is challenging to have one general COW format - for instance
> what is good for the Android ecosystem may not be useful for the
> enterprise world.
> For ex: Most of the space savings in Android comes from COPY operation i.e
> for an incremental OTA, we would have metadata which states:
> 
> COPY BLOCK X -> BLOCK Y
> 
> There is no compression involved with these operations. Compression is only
> when a block is "replaced". All these are too specific to the Android ecosystem.

Why does Android OTA need the COPY operation? If a file is not changed by 
the update, the file could be placed at the same location and no update of 
the file is needed. If a file is changed, it is improbable that the new 
file will contain permutation of blocks of the old file, so I don't see 
how COPY will help here.

Mikulas