manila/doc/source/admin/shared-file-systems-key-concepts.rst

Key concepts

Share

In the Shared File Systems service share is the fundamental resource unit allocated by the Shared File System service. It represents an allocation of a persistent, readable, and writable filesystems. Compute instances access these filesystems. Depending on the deployment configuration, clients outside of OpenStack can also access the filesystem.

Note

A share is an abstract storage object that may or may not directly map to a "share" concept from the underlying storage provider. See the description of share instance for more details.

Share instance

This concept is tied with share and represents created resource on specific back end, when share represents abstraction between end user and back-end storages. In common cases, it is one-to-one relation. One single share has more than one share instance in two cases:

• When share migration is being applied
• When share replication is enabled

Therefore, each share instance stores information specific to real allocated resource on storage. And share represents the information that is common for share instances. A user with member role will not be able to work with it directly. Only a user with admin role has rights to perform actions against specific share instances.

Snapshot

A snapshot is a point-in-time, read-only copy of a share. You can create Snapshots from an existing, operational share regardless of whether a client has mounted the file system. A snapshot can serve as the content source for a new share. Specify the Create from snapshot option when creating a new share on the dashboard.

Storage Pools

With the Kilo release of OpenStack, Shared File Systems can use storage pools. The storage may present one or more logical storage resource pools that the Shared File Systems service will select as a storage location when provisioning shares.

Share Type

Share type is an abstract collection of criteria used to characterize shares. They are most commonly used to create a hierarchy of functional capabilities. This hierarchy represents tiered storage services levels. For example, an administrator might define a premium share type that indicates a greater level of performance than a basic share type. Premium represents the best performance level.

Share Access Rules

Share access rules define which users can access a particular share. For example, administrators can declare rules for NFS shares by listing the valid IP networks which will access the share. List the IP networks in CIDR notation.

Security Services

Security services allow granular client access rules for administrators. They can declare rules for authentication or authorization to access share content. External services including LDAP, Active Directory, and Kerberos can be declared as resources. Examine and consult these resources when making an access decision for a particular share. You can associate Shares with multiple security services, but only one service per one type.

Share Networks

A share network is an object that defines a relationship between a project network and subnet, as defined in an OpenStack Networking service or Compute service. The share network is also defined in shares created by the same project. A project may find it desirable to provision shares such that only instances connected to a particular OpenStack-defined network have access to the share. Also, security services can be attached to share networks, because most of auth protocols require some interaction with network services.

The Shared File Systems service has the ability to work outside of OpenStack. That is due to the StandaloneNetworkPlugin. The plugin is compatible with any network platform, and does not require specific network services in OpenStack like Compute or Networking service. You can set the network parameters in the manila.conf file.

Share Servers

A share server is a logical entity that hosts the shares created on a specific share network. A share server may be a configuration object within the storage controller, or it may represent logical resources provisioned within an OpenStack deployment used to support the data path used to access shares.

Share servers interact with network services to determine the appropriate IP addresses on which to export shares according to the related share network. The Shared File Systems service has a pluggable network model that allows share servers to work with different implementations of the Networking service.