diff options
| author | Hannes Reinecke | 2020-05-11 10:24:30 +0200 |
|---|---|---|
| committer | Mike Snitzer | 2020-05-20 17:09:43 -0400 |
| commit | bd5c40313a1467e4683d92456fc5219d94823f24 (patch) | |
| tree | a31a375c24e02dba81faa6daf64204e63e0190fb /Documentation/admin-guide | |
| parent | dc076c838f65723325001c977b39e55fc6ba0fa7 (diff) | |
dm zoned: metadata version 2
Implement handling for metadata version 2. The new metadata adds a
label and UUID for the device mapper device, and additional UUID for
the underlying block devices.
It also allows for an additional regular drive to be used for
emulating random access zones. The emulated zones will be placed
logically in front of the zones from the zoned block device, causing
the superblocks and metadata to be stored on that device.
The first zone of the original zoned device will be used to hold
another, tertiary copy of the metadata; this copy carries a generation
number of 0 and is never updated; it's just used for identification.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'Documentation/admin-guide')
| -rw-r--r-- | Documentation/admin-guide/device-mapper/dm-zoned.rst | 34 |
1 files changed, 27 insertions, 7 deletions
diff --git a/Documentation/admin-guide/device-mapper/dm-zoned.rst b/Documentation/admin-guide/device-mapper/dm-zoned.rst index 7547ce635161..553752ea2521 100644 --- a/Documentation/admin-guide/device-mapper/dm-zoned.rst +++ b/Documentation/admin-guide/device-mapper/dm-zoned.rst @@ -37,9 +37,13 @@ Algorithm dm-zoned implements an on-disk buffering scheme to handle non-sequential write accesses to the sequential zones of a zoned block device. Conventional zones are used for caching as well as for storing internal -metadata. +metadata. It can also use a regular block device together with the zoned +block device; in that case the regular block device will be split logically +in zones with the same size as the zoned block device. These zones will be +placed in front of the zones from the zoned block device and will be handled +just like conventional zones. -The zones of the device are separated into 2 types: +The zones of the device(s) are separated into 2 types: 1) Metadata zones: these are conventional zones used to store metadata. Metadata zones are not reported as useable capacity to the user. @@ -127,6 +131,13 @@ resumed. Flushing metadata thus only temporarily delays write and discard requests. Read requests can be processed concurrently while metadata flush is being executed. +If a regular device is used in conjunction with the zoned block device, +a third set of metadata (without the zone bitmaps) is written to the +start of the zoned block device. This metadata has a generation counter of +'0' and will never be updated during normal operation; it just serves for +identification purposes. The first and second copy of the metadata +are located at the start of the regular block device. + Usage ===== @@ -138,12 +149,21 @@ Ex:: dmzadm --format /dev/sdxx -For a formatted device, the target can be created normally with the -dmsetup utility. The only parameter that dm-zoned requires is the -underlying zoned block device name. Ex:: - echo "0 `blockdev --getsize ${dev}` zoned ${dev}" | \ - dmsetup create dmz-`basename ${dev}` +If two drives are to be used, both devices must be specified, with the +regular block device as the first device. + +Ex:: + + dmzadm --format /dev/sdxx /dev/sdyy + + +Fomatted device(s) can be started with the dmzadm utility, too.: + +Ex:: + + dmzadm --start /dev/sdxx /dev/sdyy + Information about the internal layout and current usage of the zones can be obtained with the 'status' callback from dmsetup: |