openstack/fuel-specs
Code Issues Proposed changes
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fuel-specs/specs/6.1/cinder-vmdk-role.rst
Andrey Danin 13c3f63e04 Add a blueprint about cinder-vmdk-role 
"Add a separate role for Cinder with VMDK backend" blueprint.

Blueprint: cinder-vmdk-role
Change-Id: I380ef956ee9618eda16412bd550c142e78443afa
2015-01-27 18:43:21 +03:00

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Add a separate role for Cinder with VMDK backend
================================================
https://blueprints.launchpad.net/fuel/+spec/cinder-vmdk-role
When vCenter is used as a hypervisor it can use volumes only from Cinder VMDK.
And vise versa: KVM as a hypervisor cannot mount volumes from Cinder VMDK.
In case of Multi-HV support with both vCenter and KVM Compute nodes deployed,
it's necessary to deploy Cinder with multiple backends - VMDK plus LVM/Ceph.
A new role "Cinder with VMDK" should be introduced to provide this opportunity.
Problem description
===================
As it was said before, there is no universal Block Storage solution for both
vCenter and KVM hypervisors in Fuel out-of-box. Storage types for different
hypervisors:
* For KVM, it's Cinder with LVM or Ceph backend
* For vCenter, it's Cinder with VMDK backend
Fuel can not deploy cinder with LVM or Ceph backend and with VMDK backend
simultaneously only one backend for the whole environment. It happens because
Fuel 6.0 uses the only 'Cinder' role to deploy both backend types. An actual
backend type is selected in Puppet depending on hypervisor type. Such workflow
contradicts with the main Fuel idea - keep as more business logic in Nailgun as
we can. Also, the only 'Cinder' role makes it hard to deploy VMDK and
LVM/Ceph backends in one environment simultaneously.
I want to cover the following use case within blueprint [5]
Be able to deploy Cinder VMDK backend simultaneously with any other Cinder
backends.
Proposed change
===============
Introduce a new node role called 'cinder-vmware'. The role will deploy Cinder
with VMDK backend. A Puppet code should be slightly refactored to use
'node[role]' value instead of 'libvirt_type==vcenter' to deploy Cinder VMDK
backend.
An old role 'cinder' should keep deploying Cinder with LVM or Ceph. For
clarification sake, it can be also renamed to 'cinder-qemu'.
The following should be done:
- Remove the 'VMware vCenter for volumes (Cinder)' option from the UI wizard
and the Settings tab of the Fuel web UI. Keep 'Default (LVM)' and 'Ceph'
only.
- vCenter settings for Cinder should be always available on the VMware Tab of
the Fuel web UI.
- The new role should always be available if vCenter instance was added to
environment so that it can be shared with any other role.
- It's allowed to deploy more than one node with the 'cinder-vmware' role.
- It's not necessary to use Pacemaker for that Cinder service. HA will be
achieved by deploying multiple Cinder instances with the same 'hostname'
stanza and vCenter settings in cinder.conf.
- For provide possibilities combine cinder-vmware and cinder-qemu roles on the
same node cinder-vmware role should use different name for config file.
cinder-vmware.conf will be good choise.
- Nailgun should validate parameters before starting deployment to ensure that
all the necessary vCenter credentials are provided.
Alternatives
------------
There are no vital alternatives from my point of view.
Data model impact
-----------------
None.
REST API impact
---------------
None.
Upgrade impact
--------------
No special upgrade impact.
The new role will be provided with a new release. A Nailgun part should take
proper account of release version and disable itself for old releases. Puppet
manifests are located in different directories for different Fuel versions.
Security impact
---------------
None.
Notifications impact
--------------------
Two more notifications will be added into the Fuel web UI.
#. In "Deployed Changes" window: if there is one or more vCenter instance
added and cinder VMDK backend is enabled , but no Cinder VMDK roles. The
message should be the following: "In order to use volumes with vCenter
instances, please add at least one 'Cinder with VMDK' role."
#. In "Deployed Changes" window: if there is an HA environment but the only
node with "Cinder with VMDK" role is provided. The message should be the
following: "To provide HA for Cinder with VMDK backend, please select the
'Cinder with VMDK' role for at least two nodes."
One error message will be added.
#. If the role 'cinder-vmware' is used for environment but vCenter credentials
for Cinder incomplete or has wrong format, Nailgun should fail
'CheckBeforeDeploymentTask' task with the message:
"The following errors happend:
<list of errors>"
Other end user impact
---------------------
The new role should be presented on UI. It can be combined with any other role.
Performance Impact
------------------
A little more network bandwith will be consumed.
Other deployer impact
---------------------
None
Developer impact
----------------
Part of fuel-library, which deploys cinder-node will be reverted to state
before support of vmdk was enabled. New role deployment will be realized as an
independent task for granular deployment according to [4].
Implementation
==============
Assignee(s)
-----------
Primary assignee:
Igor Gajsin - igajsin
Core reviewers:
Sergii Golovatiuk - sgolovatiuk
Other contributors:
UI part: Anton Zemlyanov - azemlyanov
Nailgun part: Andriy Popovych - popovych-andrey
QA section: Oleksandr Kosse - okosse, Tanya Dubyk - tdubyk
Work Items
----------
There are three nearly independent parts of implementation:
#. Append to Fuel new role and notifications. Provide possibilities for
separate configuration of cinder and cinder-vmware nodes.
#. Change puppet manifests for create and configure new role. Clean old class
from parameters of vmdk.
#. Create or modify the corresponding system and OSTF tests.
Dependencies
============
No strict dependencies.
Possible dependencies are:
* Granular deployment feature [1].
* VMware: Dual hypervisor support (vCenter and KVM in one environment) [2].
* VMware UI Settings Tab for FuelWeb [3].
Testing
=======
Our system tests are already good enough covers use-case of using cinder. But
this tests depend on ostf tests, which know nothing about availability zones.
Therefore OSTF tests can't test how cinder works in multiple availability zones
environment. And surely tests, which based on OSTF, are also useless.
This problem will be fixed in blueprint [3]. When it happens, system tests
should be changed for using with availability zones.
Before it the QA team may perform manual testing of declared features.
Documentation Impact
====================
There are several changes in Users' Guide:
#. Change the corresponding screenshots.
#. Add description of new role.
References
==========
[1] Granular deployment feature
(https://blueprints.launchpad.net/fuel/+spec/granular-deployment-based-on-tasks)
[2] VMware: Dual hypervisor support (vCenter and KVM in one environment)
(https://blueprints.launchpad.net/fuel/+spec/vmware-dual-hypervisor)
[3] VMware UI Settings Tab for FuelWeb
(https://blueprints.launchpad.net/fuel/+spec/vmware-ui-setting)
[4] Modify Fuel Library to become more modular
(https://blueprints.launchpad.net/fuel/+spec/fuel-library-modularization)
[5] VMware: Add a separate role for Cinder with VMDK backend
(https://blueprints.launchpad.net/fuel/+spec/cinder-vmdk-role)
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