Mmuzaf commented on a change in pull request #8128: URL: https://github.com/apache/ignite/pull/8128#discussion_r484835962
########## File path: docs/_docs/persistence/snapshot.adoc ########## @@ -0,0 +1,181 @@ += Snapshots and recovery + +== Overview + +Apache Ignite 2.9 comes with an ability to create fully consistent cluster-wide snapshots for deployments with +the link:persistence/native-persistence[Ignite Native Persistence]. You can create at runtime any number of snapshots +of all configured persistent cache groups. The snapshot is a consistent copy of all cache group data files (except +structures used for crash recovery) for each baseline node in a cluster. Since data of persistent cache groups stored +on disk in files on each node (cache group partition files, configuration files, binary metadata) the snapshot will +contain a copy of the same files with keeping Ignite cluster node data directory structure and the node consistent ids. + +*Snapshot Consistency.* + +All snapshots you created are fully consistent in terms of concurrent cluster-wide operations and all ongoing changes of +system files on the local node. Primary and backup cache group partitions will be also fully consistent in created +snapshots. + +The cluster-wide snapshot consistency achieved by triggering the +link:https://cwiki.apache.org/confluence/display/IGNITE/%28Partition+Map%29+Exchange+-+under+the+hood[Partition-Map-Exchange] +procedure. Doing this the cluster will eventually get a point in time when all previously started transactions +finished on primary and backups, and new ones are hold until a new snapshot operation will be started. + +The local system files consistency (e.g. cache group partition files, binary metadata files, configuration files) achieved +by copying them to the destination snapshot directory with tracking all concurrent ongoing changes. Tracking concurrent +changes during copying of cache group partition files will require additional space in Ignite system directory. + +*Snapshot Structure.* + +The created snapshot has the same +link:https://cwiki.apache.org/confluence/display/IGNITE/Ignite+Persistent+Store+-+under+the+hood#IgnitePersistentStoreunderthehood-FoldersStructure[Directory Structure] +as the Ignite native persistence does with keeping nodes `consistentId` in snapshot directory. The `wal` directory will Review comment: This is how the sentence will look like after the page will be compiled: ``` A configured Ignite native persistence directory requires additional disk space (up to the current size of this directory). ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
