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doc: Add upmap options to osdmaptool man page and give example

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Signed-off-by: David Zafman <dzafman@redhat.com>
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David Zafman 2019-12-17 19:38:51 -08:00
parent e42a6ccb18
commit 184e9d1ae3
2 changed files with 49 additions and 18 deletions
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28
doc/man/8/osdmaptool.rst
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@ -15,6 +15,10 @@ Synopsis
[--pgbits *bitsperosd* ] ] [--clobber]
| **osdmaptool** *mapfilename* [--import-crush *crushmap*]
| **osdmaptool** *mapfilename* [--export-crush *crushmap*]
| **osdmaptool** *mapfilename* [--upmap *file*] [--upmap-max *max-optimizations*]
[--upmap-deviation *max-deviation*] [--upmap-pool *poolname*]
[--upmap-save *file*] [--upmap-save *newosdmap*]
| **osdmaptool** *mapfilename* [--upmap-cleanup] [--upmap-save *newosdmap*]
Description
@ -133,6 +137,30 @@ Options
include default pool when creating map
.. option:: --upmap-cleanup <file>
clean up pg_upmap[_items] entries, writing commands to <file> [default: - for stdout]
.. option:: --upmap <file>
calculate pg upmap entries to balance pg layout writing commands to <file> [default: - for stdout]
.. option:: --upmap-max <max-optimizations>
set max upmap entries to calculate [default: 10]
.. option:: --upmap-deviation <max-deviation>
max deviation from target [default: 1]
.. option:: --upmap-pool <poolname>
restrict upmap balancing to 1 pool or the option can be repeated for multiple pools
.. option:: --upmap-save
write modified OSDMap with upmap changes
Example
=======

39
doc/rados/operations/upmap.rst
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@ -23,14 +23,12 @@ use with::
ceph features
A word of caution
Balancer module
-----------------
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.
The new `balancer` module for ceph-mgr will automatically balance
the number of PGs per OSD. See ``Balancer``
Until then,
Offline optimization
--------------------
@ -43,7 +41,8 @@ Upmap entries are updated with an offline optimizer built into ``osdmaptool``.
#. Run the optimizer::
osdmaptool om --upmap out.txt [--upmap-pool <pool>] [--upmap-max <max-count>] [--upmap-deviation <max-deviation>]
osdmaptool om --upmap out.txt [--upmap-pool <pool>]
[--upmap-max <max-optimizations>] [--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
@ -52,24 +51,28 @@ Upmap entries are updated with an offline optimizer built into ``osdmaptool``.
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-optimizations`` value is the maximum number of upmap entries to
identify in the run. The default is `10` like the ceph-mgr balancer module,
but you should use a larger number if you are doing offline optimization.
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 ``max-deviation`` value defaults to `1`. If an OSD PG count
varies from the computed target number by less than or equal
to 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::
#. Apply the changes::
source out.txt
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.
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``.
passing ``--debug-osd 10`` and even more with ``--debug-crush 10``
to ``osdmaptool``.