On 3/24/20 12:02 PM, Bob Liu wrote:
Motivation:
dm-zoned exposes a zoned block device(ZBC) as a regular block device by storing
metadata and buffering random writes in its conventional zones.
This way is not flexible, there must be enough conventional zones and the
performance may be constrained.
This patchset split the metadata from zoned device to an extra regular device,
with aim to increase the flexibility and potential performance.
For example, now we can store metadata in a faster device like persistent memory.
Also random writes can go to the regular devices in this version.
Usage(will send user space patches later):
dmzadm --format $zoned_dev --regular=$regu_dev --force
echo "0 $size zoned $regu_dev $zoned_dev" | dmsetup create $dm-zoned-name
v2:
* emulate regular device zone info
* support write both metadata and random writes to regular dev
Bob Liu (3):
dm zoned: rename dev name to zoned_dev
dm zoned: introduce regular device to dm-zoned-target
dm zoned: add regular device info to metadata
drivers/md/dm-zoned-metadata.c | 205 +++++++++++++++++++++++++++--------------
drivers/md/dm-zoned-target.c | 205 +++++++++++++++++++++++------------------
drivers/md/dm-zoned.h | 53 ++++++++++-
3 files changed, 299 insertions(+), 164 deletions(-)
Well, surprise, surprise, both our patchsets are largely identical ...
So how to proceed? I guess if you were using 'cdev' instead of
'regu_dm_dev' we should be having an overlap of about 90 percent.
The main difference between our implementation is that I didn't move the
metadata to the cache/regulard device, seeing that dmzadm will only
write metadata onto the zoned device.
I would rather keep it that way (ie storing metadata on the zoned
device, too, if possible) as we would be keeping backwards compability
with that.
And we could always move metadata to the cache/regular device in a later
patch; for doing it properly we'll need to update the metadata anyway as
we need to introduce UUIDs to stitch those devices together.
Remember, one my have more than one zoned device and regular device...
Should I try to merge both patchsets and send them out as an RFC?
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
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