Re: Creating detached dm-integrity hashes for existing disk

(Please keep me in CC, as I'm not subscribed to the mailing list.)


On Tue, Nov 22, 2022 at 3:34 PM Milan Broz <[email protected]> wrote:
> There still can be some bugs (mainly for bitmap mode that is very rarely used;
> better test it in internal hash mode).


I am interested in the bitmap mode because I want the drive to behave
as "write-through", and I care more about writes reaching the data
disk, than computing the integrity.  In my case the integrity is only
an afterthought, or optional, and I want to be able to just remove it
and use the underlying data disk directly without losing any writes.

If I understand correctly, with journaled mode the data is first
written to the journal, hashed, and then written to the data disk.
Thus if something happens with the metadata disk, the data disk could
have some writes missing.

Are there any serious disadvantages in using bitmap mode vs journaled mode?

Thanks,
Ciprian.