Proposed blueprint for VMware storage based policy support
Part of blueprint vmware-spbm-support. Change-Id: Ia3cda1e2f031d708246285abcf68dd80ceedc7c0
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Gary Kotton
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specs/juno/vmware-spbm-support.rst
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specs/juno/vmware-spbm-support.rst
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This work is licensed under a Creative Commons Attribution 3.0 Unported
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License.
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http://creativecommons.org/licenses/by/3.0/legalcode
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======================================
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Storage Policy Based Management (SPBM)
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======================================
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https://blueprints.launchpad.net/nova/+spec/vmware-spbm-support
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The feature will enable an OpenStack environment to take advantage of
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backend storage policies to provide differential services to tenants.
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Problem description
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===================
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Enable administrators and tenants to take advantage of backend storage
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policies. The storage admin first creates storage profiles in VC based
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on the storage vendor provided capabilities and/or tag based capabilities
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of the underlying storage infrastructure. Refer to
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http://pubs.vmware.com/vsphere-55/topic/com.vmware.vsphere.storage.doc/GUID-A8BA9141-31F1-4555-A554-4B5B04D75E54.html
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to learn more about storage profiles on VC.
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The disk(s) of the virtual machine will be placed on the storage that
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matches the storage policy. This can for example provide preferential
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services to the user. For example the user will have an option of
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selecting 'gold', 'silver' or 'bronze' storage. 'gold' can be for
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applications that require fast and reliable results. 'bronze' can be
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for a background VM running in the evening doing maintenance.
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The spawn method currently selects the ‘best’ datastore to use. The
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administrator is able to select one or more datastores for selection
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by configuring a datastore regular expression. This logic will not
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be required if the instance flavor contain extra spec information
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that is relevant to the SPBM. That is, the SPBM information will be
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used for the datastore selection.
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Proposed change
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===============
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In order for Nova to provide SPBM we will need to address the following:
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* Enabling the tenant to make use of storage policies. The goal here
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will be to provide the administrator with the necessary tools to
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provide differential storage services to the tenant. More specifically
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the administrator will be able to leverage capabilities provided by the
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storage infrastructure. There are two parts:
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* Configuration. The admin will need to do the following:
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* Configure a default SPBM policy
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* Create a flavor(s) for the tenants that will enable them to make use
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of the various storage policies.
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* Tenant usage. The tenant will be able to select a flavor that has
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a storage policy.
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* Driver support for the storage policies.
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* This entails using the information passed by the tenant to the driver.
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More specifically the storage policy will be passed as flavor metadata.
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The driver will need to make use of a different endpoint to access the storage
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policies on the VC. This will require a new configuration variable, that is,
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the PBM WSDL location will need to be defined.
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NOTE: all of the nodes will share the same storage so there will not be any
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issues regarding rescheduling.
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The change will not affect the cached images. This is only where the disk
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for the VM will be placed.
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The flavor extra spec ‘image:storage_policy’ will drive the datastore
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selection. In the event that this flag is not present and the pbm_enabled
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is set in the configuration file then we will make use of a configured default
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policy. That is, if this is present then it will be used to get the list of
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datastores that can be used for selection. If not then we will use the list of
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datastores that can be accessed by the cluster.
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If this exists then we will validate that the policy exists.
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If not then an exception will be thrown. We will then proceed to get the moref
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and datastore of the datastore that is relevant to this policy
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pseudo code::
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profile_ids = pbmServiceContent.profileManager.pbmQueryProfile()
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profiles = pbmRetrieveContent(profile_ids)
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profiles.find(name=profile_name)
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Query Matching ‘datastore’ entities for the profile. API :-
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pbmQueryMatchingHub
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If this does not exist then we will proceed to the select the datastore as
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before.
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The list of datastores will be processed by the existing code to select the
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best fit.
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Alternatives
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------------
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At the moment there is no way that a administrator can provide differential
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storage services to a tenant.
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Data model impact
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-----------------
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There are no data model changes. The information is passed from the tenant to
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the driver via flavor metadata (extraspecs). The driver in turn will use this
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information to assign the correct storage.
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REST API impact
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---------------
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None
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Security impact
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---------------
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None
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Notifications impact
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--------------------
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None
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Other end user impact
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---------------------
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The cloud provider will provide a flavor to the tenant that will enable them
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to have preferential storage capabilities.
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Performance Impact
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------------------
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None
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Other deployer impact
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---------------------
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There are 3 new configuration variables (both in the vmware section):
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* pbm_wsdl_location - PBM service WSDL file location URL. e.g.
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file:///opt/SDK/spbm/wsdl/pbmService.wsdl. This will be optional. This
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value is a string. The default is None (not set).
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* pbm_enabled - status of storage policy based placement of instances.
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This value is a boolean. Default is False.
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* pbm_default_policy - The PBM default policy. If pbm_enabled
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is set and there is no defined storage policy for the specific request
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then this policy will be used. This value is a string. The default policy
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is defined out of band by the administrator on the Virtual Center. The
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default is None (not set).
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An admin user will create a new flavor either via the dashboard or the CLI.
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The flavor extra spec will have a key ‘image:storage_policy’. The admin
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will associate this this a predfined storage policy on the VC.
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Developer impact
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----------------
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None
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Implementation
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==============
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None
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Assignee(s)
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-----------
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Primary assignee:
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garyk
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smurugesan
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Other contributors:
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rgerganov
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Work Items
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----------
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Code was posted in the Icehouse cycle:
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* SPBM support (part of oslo integration)
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* Add support for default pbm policy
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* Get storage policy from flavor
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* Use storage policy in datastore selection
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* Associate instance with storage policy
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Dependencies
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============
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None
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Testing
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=======
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This requires 3rd party testing. It is not possible to be tested by the current
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gate.
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Documentation Impact
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====================
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Configuration variables and their usage need to be documented.
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Flavor creation and management should be discussed too. That is, the flavor
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extra spec will need to contain the policy. The key will be:
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'image:storage_policy' and the values can be for example 'gold', 'silver',
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etc.
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References
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==========
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https://docs.google.com/document/d/14Fr76WsFxBPfQJHRdy389IxlxZHXq-Kr83PeCXgDP1M/edit
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