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Accessibility for multi-region Object Storage

In multi-region Object Storage utilizing separate database backends, objects are retrievable from an alternate location if the default_project_id for a user in the keystone database is the same across each database backend.

Important

It is recommended to perform the following steps before a failure occurs to avoid having to dump and restore the database.

If a failure does occur, follow these steps to restore the database from the Primary (failed) Region:

1. Record the Primary Region output of the default_project_id for the specified user from the user table in the keystone database:

   Note

   The user is admin in this example.

   # mysql -e "SELECT default_project_id from keystone.user WHERE \
     name='admin';"
   
   +----------------------------------+
   | default_project_id               |
   +----------------------------------+
   | 76ef6df109744a03b64ffaad2a7cf504 |
   +-----------------—————————————————+
   

2. Record the Secondary Region output of the default_project_id for the specified user from the user table in the keystone database:

   # mysql -e "SELECT default_project_id from keystone.user WHERE \
     name='admin';"
   
   +----------------------------------+
   | default_project_id               |
   +----------------------------------+
   | 69c46f8ad1cf4a058aa76640985c     |
   +----------------------------------+
   

3. In the Secondary Region, update the references to the project_id to match the ID from the Primary Region:

   # export PRIMARY_REGION_TENANT_ID="76ef6df109744a03b64ffaad2a7cf504"
   # export SECONDARY_REGION_TENANT_ID="69c46f8ad1cf4a058aa76640985c"
   
   # mysql -e "UPDATE keystone.assignment set \
   target_id='${PRIMARY_REGION_TENANT_ID}' \
   WHERE target_id='${SECONDARY_REGION_TENANT_ID}';"
   
   # mysql -e "UPDATE keystone.user set \
   default_project_id='${PRIMARY_REGION_TENANT_ID}' WHERE \
   default_project_id='${SECONDARY_REGION_TENANT_ID}';"
   
   # mysql -e "UPDATE keystone.project set \
   id='${PRIMARY_REGION_TENANT_ID}' WHERE \
   id='${SECONDARY_REGION_TENANT_ID}';"
   

The user in the Secondary Region now has access to objects PUT in the Primary Region. The Secondary Region can PUT objects accessible by the user in the Primary Region.