import ceph 16.2.6

[ceph.git] / ceph / doc / rados / operations / placement-groups.rst

diff --git a/ceph/doc/rados/operations/placement-groups.rst b/ceph/doc/rados/operations/placement-groups.rst
index 699c26f8e30b9a85ad659d595d66c0814bc3ee7b..947fdb1568cb43ff7d621aa0c7e7837211ad93fd 100644 (file)
--- a/ceph/doc/rados/operations/placement-groups.rst
+++ b/ceph/doc/rados/operations/placement-groups.rst
@@ -41,10 +41,10 @@ the PG count with this command::
 
 Output will be something like::
 
-   POOL    SIZE  TARGET SIZE  RATE  RAW CAPACITY   RATIO  TARGET RATIO  EFFECTIVE RATIO PG_NUM  NEW PG_NUM  AUTOSCALE
-   a     12900M                3.0        82431M  0.4695                                     8         128  warn
-   c         0                 3.0        82431M  0.0000        0.2000           0.9884      1          64  warn
-   b         0        953.6M   3.0        82431M  0.0347                                     8              warn
+   POOL    SIZE  TARGET SIZE  RATE  RAW CAPACITY   RATIO  TARGET RATIO  EFFECTIVE RATIO BIAS PG_NUM  NEW PG_NUM  AUTOSCALE PROFILE 
+   a     12900M                3.0        82431M  0.4695                                          8         128  warn      scale-up
+   c         0                 3.0        82431M  0.0000        0.2000           0.9884  1.0      1          64  warn      scale-down
+   b         0        953.6M   3.0        82431M  0.0347                                          8              warn      scale-down
 
 **SIZE** is the amount of data stored in the pool. **TARGET SIZE**, if
 present, is the amount of data the administrator has specified that
@@ -77,6 +77,10 @@ ratio takes precedence.
 The system uses the larger of the actual ratio and the effective ratio
 for its calculation.
 
+**BIAS** is used as a multiplier to manually adjust a pool's PG based
+on prior information about how much PGs a specific pool is expected
+to have.
+
 **PG_NUM** is the current number of PGs for the pool (or the current
 number of PGs that the pool is working towards, if a ``pg_num``
 change is in progress).  **NEW PG_NUM**, if present, is what the
@@ -84,9 +88,13 @@ system believes the pool's ``pg_num`` should be changed to.  It is
 always a power of 2, and will only be present if the "ideal" value
 varies from the current value by more than a factor of 3.
 
-The final column, **AUTOSCALE**, is the pool ``pg_autoscale_mode``,
+**AUTOSCALE**, is the pool ``pg_autoscale_mode``
 and will be either ``on``, ``off``, or ``warn``.
 
+The final column, **PROFILE** shows the autoscale profile 
+used by each pool. ``scale-up`` and ``scale-down`` are the
+currently available profiles.
+
 
 Automated scaling
 -----------------
@@ -113,6 +121,28 @@ example, a pool that maps to OSDs of class `ssd` and a pool that maps
 to OSDs of class `hdd` will each have optimal PG counts that depend on
 the number of those respective device types.
 
+The autoscaler uses the `scale-down` profile by default, 
+where each pool starts out with a full complements of PGs and only scales 
+down when the usage ratio across the pools is not even. However, it also has 
+a `scale-up` profile, where it starts out each pool with minimal PGs and scales
+up PGs when there is more usage in each pool.
+
+With only the `scale-down` profile, the autoscaler identifies
+any overlapping roots and prevents the pools with such roots
+from scaling because overlapping roots can cause problems
+with the scaling process.
+
+To use the `scale-up` profile::
+
+  ceph osd pool set autoscale-profile scale-up
+
+To switch back to the default `scale-down` profile::
+
+  ceph osd pool set autoscale-profile scale-down
+
+Existing clusters will continue to use the `scale-up` profile.
+To use the `scale-down` profile, users will need to set autoscale-profile `scale-down`,
+after upgrading to a version of Ceph that provides the `scale-down` feature.
 
 .. _specifying_pool_target_size: