1. OTA does not control placement of files. That’s done by file systems(ext4)
2. OTA work at block device level. Not file level
3. Often times, a file would have few of its blocks changed/shuffled, and rest of the blocks retain old content.
On Mon, Nov 29, 2021 at 06:05 Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote:
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
Sincerely,
Kelvin Zhang
-- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
