openstack
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ha-guide
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Move the memcached summary into a page specific to memcached 

Change-Id: I46fb5f3a1781c023802ae38f31ca65456b9f8d9b
This commit is contained in:
Andrew Beekhof 2015-11-16 13:31:17 +11:00 committed by KATO Tomoyuki
parent fa3b313779
commit 66e084e089
3 changed files with 22 additions and 15 deletions
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21
doc/ha-guide/source/controller-ha-memcached.rst Normal file
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===================
Memcached
===================
Memcached is a general-purpose distributed memory caching system. It
is used to speed up dynamic database-driven websites by caching data
and objects in RAM to reduce the number of times an external data
source must be read.
Memcached is a memory cache demon that can be used by most OpenStack
services to store ephemeral data, such as tokens.
Access to memcached is not handled by HAproxy because replicated
access is currently only in an experimental state. Instead OpenStack
services must be supplied with the full list of hosts running
memcached.
The Memcached client implements hashing to balance objects among the
instances. Failure of an instance only impacts a percentage of the
objects and the client automatically removes it from the list of
instances. The SLA is several minutes.

1
doc/ha-guide/source/controller-ha.rst
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@ -13,6 +13,7 @@ and must talk to all other services.
controller-ha-haproxy.rst
controller-ha-vip.rst
controller-ha-galera.rst
controller-ha-memcached.rst
controller-ha-rabbitmq.rst
controller-ha-keystone.rst
controller-ha-telemetry.rst

15
doc/ha-guide/source/intro-ha-controller.rst
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@ -60,18 +60,3 @@ for doing this is keepalived.
intro-ha-arch-pacemaker.rst
intro-ha-arch-keepalived.rst
Memcached back end
~~~~~~~~~~~~~~~~~~
Memcached is a memory cache demon that can be used
by most OpenStack services to store ephemeral data, such as tokens.
Although Memcached does not support
typical forms of redundancy such as clustering,
OpenStack services can use almost any number of instances
by configuring multiple hostnames or IP addresses.
The Memcached client implements hashing
to balance objects among the instances.
Failure of an instance only impacts a percentage of the objects
and the client automatically removes it from the list of instances.
The SLA is several minutes.