+++ /dev/null
-Using the pg-upmap
-==================
-
-Starting in Luminous v12.2.z there is a new *pg-upmap* exception table
-in the OSDMap that allows the cluster to explicitly map specific PGs to
-specific OSDs. This allows the cluster to fine-tune the data
-distribution to, in most cases, perfectly distributed PGs across OSDs.
-
-The key caveat to this new mechanism is that it requires that all
-clients understand the new *pg-upmap* structure in the OSDMap.
-
-Enabling
---------
-
-To allow use of the feature, you must tell the cluster that it only
-needs to support luminous (and newer) clients with::
-
- ceph osd set-require-min-compat-client luminous
-
-This command will fail if any pre-luminous clients or daemons are
-connected to the monitors. You can see what client versions are in
-use with::
-
- ceph features
-
-A word of caution
------------------
-
-This is a new feature and not very user friendly. At the time of this
-writing we are working on a new `balancer` module for ceph-mgr that
-will eventually do all of this automatically.
-
-Until then,
-
-Offline optimization
---------------------
-
-Upmap entries are updated with an offline optimizer built into ``osdmaptool``.
-
-#. Grab the latest copy of your osdmap::
-
- ceph osd getmap -o om
-
-#. Run the optimizer::
-
- osdmaptool om --upmap out.txt [--upmap-pool <pool>] [--upmap-max <max-count>] [--upmap-deviation <max-deviation>]
-
- It is highly recommended that optimization be done for each pool
- individually, or for sets of similarly-utilized pools. You can
- specify the ``--upmap-pool`` option multiple times. "Similar pools"
- means pools that are mapped to the same devices and store the same
- kind of data (e.g., RBD image pools, yes; RGW index pool and RGW
- data pool, no).
-
- The ``max-count`` value is the maximum number of upmap entries to
- identify in the run. The default is 100, but you may want to make
- this a smaller number so that the tool completes more quickly (but
- does less work). If it cannot find any additional changes to make
- it will stop early (i.e., when the pool distribution is perfect).
-
- The ``max-deviation`` value defaults to `.01` (i.e., 1%). If an OSD
- utilization varies from the average by less than this amount it
- will be considered perfect.
-
-#. The proposed changes are written to the output file ``out.txt`` in
- the example above. These are normal ceph CLI commands that can be
- run to apply the changes to the cluster. This can be done with::
-
- source out.txt
-
-The above steps can be repeated as many times as necessary to achieve
-a perfect distribution of PGs for each set of pools.
-
-You can see some (gory) details about what the tool is doing by
-passing ``--debug-osd 10`` to ``osdmaptool``.
Code Review / stor4nfv.git / blobdiff