Arvados

It seemed reasonable to add the whole StorageClasses config section (with Default for #17696 as well as Priority for this issue). Then I forgot #17696 was already assigned to someone else and implemented the Default behavior as well.

17967-storage-classes-config @ 13b280ea288fd08e8c77300b087037635d739eaa -- developer-run-tests: #2621

• add config section with default behavior as described in #17696
• try higher-priority volumes (i.e., volumes with higher-priority storage classes) first when reading
• change keepstore behavior to write to the configured default storage classes when the client didn't specify any (previously was "disregard storage classes" in that case) -- I figured this should make the SDK side much easier
• change arv-put behavior to not specify storage classes for newly written collections/blocks if none were specified by the caller (previously was ["default"])
• TODO: update admin/storage-classes.html

• update docs

      # If you use multiple storage classes, specify them here, using
      # the storage class name as the key (in place of "SAMPLE" in
      # this sample entry).

This comment doesn't explain what a storage class is, it should either be extended a bit ("Storage classes enable you to control which volumes should be used to store the blocks of a given collection") and/or link to the documentation.

Need to mention the config changes in doc/admin/upgrading.html.textile.liquid

There's some changes to the API server behavior, perhaps that should get a test?

developer-run-tests: #2625

• add doc link to config file
• add upgrade note about adding StorageClasses section
• add/update railsapi tests for default storage classes

Tom Clegg wrote:

17967-storage-classes-config @ 7860f93d77e8690ba90e839b52e2886a08466773 -- developer-run-tests: #2625

• add doc link to config file
• add upgrade note about adding StorageClasses section
• add/update railsapi tests for default storage classes

This LGTM