anchor.diff:  Solr 8.9 introduces extensive changes to Solr's backup and restore support.
   
   A new backup format has been introduced in Solr 8.9 which replaces the previous snapshot-based backup.
  -The new backup format supports incremental backups.
  +This new format enables ‘incremental’ backups.
  +Repeated backups to a given location will take advantage of the data stored by their predecessors and will only operate on files that have changed since the previous backup.
   This is supported by default, simply by storing each backup file in the same location.
   
  -The old and new formats are not compatible, although backups in the old format can still be used to restore to Solr for the time-being.
  +The old and new formats are not compatible, although backups in the old format, a full snapshot of all files, can still be used to restore to Solr for the time-being.
   The old format is officially deprecated, and support for it is likely to be removed in Solr 9.0.
   
   For the time-being the old format can be created by defining a parameter `incremental=false`.
  
positive.code: More documentation on backups is available at <<making-and-restoring-backups.adoc#,Making and Restoring Backups>>.
  
  New Collections API commands for backups:
  * LISTBACKUP: Lists information about each backup stored at the specified repository location.
  See <<collection-management.adoc#listbackup,List Backups>> for more details.
  * DELETEBACKUP: Deletes specified backups from the repository. See <<collection-management.adoc#deletebackup,Delete Backups>> for more details.
  
negative.code: *Metrics History*
  
  The Metrics History feature, which allowed long-term storage and aggregation of Solr's metrics, has been deprecated and will be removed in 9.0.
  
  *Embedded Solr Server*
  
  When using EmbeddedSolrServer, it will no longer close CoreContainer instances that were passed to it.
  
  === Solr 8.8
  
  