[dm-devel] [PATCH RFC 0/2] dm-zoned: add cache device

[Mike Snitzer]

On Mon, Mar 23 2020 at 11:03am -0400,
Hannes Reinecke <hare at suse.de> wrote:

> Hi Damien,
> 
> as my original plan to upgrade bcache to work for SMR devices
> turned out to be more complex than anticipated I went for the
> simpler approach and added a 'cache' device for dm-zoned.
> It is using a normal device (eg '/dev/pmem0' :-), split it
> into zones of the same size of the original SMR device, and
> makes those 'virtual' zones avialable to dm-zoned in a similar
> manner than the existing 'random write' zoned.
> 
> The implementation is still a bit rough (one would need to add
> metadata to the cache device, too), but so far it seems to work
> quite well; still running after copying 300GB of data back and forth.
> 
> As usual, comments and reviews are welcome.

Not seeing why this needs to be so specialized (natively implemented in
dm-zoned).  Did you try stacking dm-writecache on dm-zoned?

Mike