Multi Store Support

Multi Store Support

Note

The Multi Store feature is introduced as EXPERIMENTAL in Rocky and its use in production systems is currently not supported. However we encourage people to use this feature for testing purposes and report the issues so that we can make it stable and fully supported in Stein release.

Scope of this document

This page describes how to enable multiple stores in glance.

Prerequisites

  • Glance version 17.0.0 or Later

  • Glance Store Library 0.25.0 or Later

  • Glance not using the Glance Registry

  • Available backends

Procedure

In this section, we discuss what configuration options are available to operators to enable multiple stores support.

  • in the [DEFAULT] options group:

    • enabled_backends must be set as a key:value pair where key represents the identifier for the store and value will be the type of the store. Valid values are one of file, http, rbd, swift, cinder, sheepdog or vmware. In order to have multiple stores operator can specify multiple key:value separated by comma.

      [DEFAULT]
      enabled_backends = fast:rbd, cheap:rbd, shared:file, reliable:file
      

      Note

      Due to the special read only nature and characteristics of the http store we do not encourage nor support configuring multiple instances of http store even though it’s possible.

  • in the [glance_store] options group:

    • default_backend must be set to one of the identifier which are defined using enabled_backends option. If default_backend is not set or if it is not representing one of the valid store drivers then it will prevent glance api service from starting.

      [glance_store]
      default_backend = fast
      
  • For each of the store identifier defined in enabled_backends section operator needs to add a new config group which will define config options related to that particular store.

    [shared]
    filesystem_store_datadir = /opt/stack/data/glance/shared_images/
    store_description = "Shared filesystem store"
    
    [reliable]
    filesystem_store_datadir = /opt/stack/data/glance/reliable
    store_description = "Reliable filesystem backend"
    
    [fast]
    store_description = "Fast rbd backend"
    rbd_store_chunk_size = 8
    rbd_store_pool = images
    rbd_store_user = admin
    rbd_store_ceph_conf = /etc/ceph/ceph.conf
    rados_connect_timeout = 0
    
    [cheap]
    store_description = "Cheap rbd backend"
    rbd_store_chunk_size = 8
    rbd_store_pool = images
    rbd_store_user = admin
    rbd_store_ceph_conf = /etc/ceph/ceph1.conf
    rados_connect_timeout = 0
    

    Note

    store_description is a new config option added to each store where operator can add meaningful description about that store. This description is displayed in the GET /v2/info/stores response.

  • For new image import workflow glance will reserve a os_staging file store identifier for staging the images data during staging operation. This should be added by default in glance-api.conf as shown below:

    [os_staging]
    filesystem_store_datadir = /opt/stack/data/glance/os_staging/
    store_description = "Filesystem store for staging purpose"
    
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