From 66e084e089cfee8d0b0d16d07ebdd2f6c10740cd Mon Sep 17 00:00:00 2001 From: Andrew Beekhof Date: Mon, 16 Nov 2015 13:31:17 +1100 Subject: [PATCH] Move the memcached summary into a page specific to memcached Change-Id: I46fb5f3a1781c023802ae38f31ca65456b9f8d9b --- .../source/controller-ha-memcached.rst | 21 +++++++++++++++++++ doc/ha-guide/source/controller-ha.rst | 1 + doc/ha-guide/source/intro-ha-controller.rst | 15 ------------- 3 files changed, 22 insertions(+), 15 deletions(-) create mode 100644 doc/ha-guide/source/controller-ha-memcached.rst diff --git a/doc/ha-guide/source/controller-ha-memcached.rst b/doc/ha-guide/source/controller-ha-memcached.rst new file mode 100644 index 00000000..4592ea12 --- /dev/null +++ b/doc/ha-guide/source/controller-ha-memcached.rst @@ -0,0 +1,21 @@ +=================== +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. diff --git a/doc/ha-guide/source/controller-ha.rst b/doc/ha-guide/source/controller-ha.rst index aac6dc73..010bf7a0 100644 --- a/doc/ha-guide/source/controller-ha.rst +++ b/doc/ha-guide/source/controller-ha.rst @@ -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 diff --git a/doc/ha-guide/source/intro-ha-controller.rst b/doc/ha-guide/source/intro-ha-controller.rst index ad8485ff..26cf2391 100644 --- a/doc/ha-guide/source/intro-ha-controller.rst +++ b/doc/ha-guide/source/intro-ha-controller.rst @@ -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.