openstack/swift
Code Issues Proposed changes

Add ring-builder dispersion command to admin guide

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This change updates the admin guide to point out the dispersion command
in swift-ring-builder and mentions the dispersion verbose table to make
it more obvious to operators.

Change-Id: I72b4c8b2d718e6063de0fdabbaf4f2b73694e0a4
This commit is contained in:
Matthew Oliver 2016-05-25 14:35:54 +10:00
parent 551e2541c3
commit b3ab715c05
2 changed files with 21 additions and 0 deletions
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17
doc/source/admin_guide.rst
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@ -98,6 +98,23 @@ This produces a great deal of output that is mostly useful if you are
either (a) attempting to fix the ring builder, or (b) filing a bug
against the ring builder.
You may notice in the rebalance output a 'dispersion' number. What this
number means is explained in :ref:`ring_dispersion` but in essence
is the percentage of partitions in the ring that have too many replicas
within a particular failure domain. You can ask 'swift-ring-builder' what
the dispersion is with::
swift-ring-builder <builder-file> dispersion
This will give you the percentage again, if you want a detailed view of
the dispersion simply add a ``--verbose``::
swift-ring-builder <builder-file> dispersion --verbose
This will not only display the percentage but will also display a dispersion
table that lists partition dispersion by tier. You can use this table to figure
out were you need to add capacity or to help tune an :ref:`ring_overload` value.
-----------------------
Scripting Ring Creation
-----------------------

4
doc/source/overview_ring.rst
View File

@ -158,6 +158,8 @@ for the ring. This means that some partitions will have more replicas than
others. For example, if a ring has 3.25 replicas, then 25% of its partitions
will have four replicas, while the remaining 75% will have just three.
.. _ring_dispersion:
**********
Dispersion
**********
@ -173,6 +175,8 @@ the dispersion metric.
A lower dispersion value is better, and the value can be used to find the
proper value for "overload".
.. _ring_overload:
********
Overload
********