diff options
Diffstat (limited to 'Documentation/admin-guide/device-mapper')
| -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: |