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Capabilities and Extra-Specs

Cloud Administrators create shared_file_systems_share_types with extra-specs to:

As an administrator, you can choose a descriptive name or provide good descriptions for your share types to convey the share type capabilities to end users. End users can view standard tenant-visible extra-specs that can let them seek required behavior and automate their applications accordingly. By design, however, all other extra-specs of a share type are not exposed to non-privileged users.

Types of Extra-Specs

The Shared File Systems service back-end storage drivers offer a wide range of capabilities. The variation in these capabilities allows cloud administrators to provide a storage service catalog to their end users. Share type extra-specs tie-in with these capabilities.

Some back-end capabilities are very specific to a storage system, and are opaque to the Shared File System service or the end users. These capabilities are invoked with the help of "scoped" extra-specs. Using scoped extra-specs is a way to provide programmatic directives to the concerned storage driver to do something during share creation or share manipulation. You can learn about the opaque capabilities through driver documentation and configure these capabilities within share types as scoped extra-specs (e.g.: hpe3par:nfs_options). The Shared File System service scheduler ignores scoped extra-specs during its quest to find the right back end to provision shares.

There are some back-end capabilities in manila that do matter to the scheduler. For our understanding, lets call these non-scoped or non-opaque capabilities. All non-scoped capabilities can be directly used as share types extra-specs. They are considered by the scheduler’s capabilities filter (and any custom filter defined by deployers).

You can get a list of non-scoped capabilities from the scheduler by using:

$ manila pool-list --detail

The non-scoped capabilities can be of three types:

Important

All extra-specs are optional, except one: driver_handles_share_servers.

Scheduler's treatment of non-scoped extra specs

The CapabilitiesFilter in the Shared File System scheduler uses the following for matching operators:

For vendor-specific non-scoped capabilities (which need to be visible to the scheduler), drivers are recommended to use the vendor prefix followed by an underscore. This is not a strict requirement, but can provide a consistent look along-side the scoped extra-specs and will be a clear indicator of vendor capabilities vs. common capabilities.

Common Capabilities

Common capabilities apply to multiple backends. Like all other backend reported capabilities, these capabilities can be used verbatim as extra_specs in share types used to create shares.

Share type common capability extra-specs that are visible to end users:

Share type common capability extra-specs that are not visible to end users:

{'thin_provisioning': 'False'}
{'thin_provisioning': '<is> False'}
{'capabilities:thin_provisioning': 'False'}
{'capabilities:thin_provisioning': '<is> False'}