From 86a4c8e143a9626ab3032f04b0f00bc5eb5c2cea Mon Sep 17 00:00:00 2001 From: EdLeafe Date: Wed, 25 Nov 2015 17:08:25 +0000 Subject: [PATCH] Docs: update the concept guide for Host topics Added text to the 'Hosts' and 'Host Actions' sections. Change-Id: Ie139810b97ab0a9bb96c928ffb794353c6f0c0ae --- api-guide/source/general_info.rst | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/api-guide/source/general_info.rst b/api-guide/source/general_info.rst index 11cefd381160..1d553cb0980a 100644 --- a/api-guide/source/general_info.rst +++ b/api-guide/source/general_info.rst @@ -115,16 +115,36 @@ In this section we focus on this related to networking. Administrator Concepts ======================= -Come APIs are largely focused on administration of Nova, and generally focus +Some APIs are largely focused on administration of Nova, and generally focus on compute hosts rather than servers. - **Hosts** - TODO + Hosts are the *physical machines* that provide the resources for the virtual + servers created in Nova. They run a ``hypervisor`` (see definition below) + that handles the actual creation and management of the virtual servers. + Hosts also run the ``Nova compute service``, which receives requests from + Nova to interact with the virtual servers on that machine. When compute + service receives a request, it calls the appropriate methods of the driver + for that hypervisor in order to carry out the request. The driver acts as + the translator from generic Nova requests to hypervisor-specific calls. + Hosts report their current state back to Nova, where it is tracked by the + scheduler service, so that the scheduler can place requests for new virtual + servers on the hosts that can best fit them. - **Host Actions** - TODO + A *host action* is one that affects the physical host machine, as opposed to + actions that only affect the virtual servers running on that machine. There + are three 'power' actions that are supported: *startup*, *shutdown*, and + *reboot*. There are also two 'state' actions: enabling/disabling the host, + and setting the host into or out of maintenance mode. Of course, carrying + out these actions can affect running virtual servers on that host, so their + state will need to be considered before carrying out the host action. For + example, if you want to call the 'shutdown' action to turn off a host + machine, you might want to migrate any virtual servers on that host before + shutting down the host machine so that the virtual servers continue to be + available without interruption. - **Hypervisors**