jojochuang commented on code in PR #436: URL: https://github.com/apache/ozone-site/pull/436#discussion_r3283690060
########## docs/05-administrator-guide/02-configuration/04-performance/11-storage-capacity-planning.md: ########## @@ -0,0 +1,142 @@ +--- +sidebar_label: Storage Capacity Planning +--- + +# Storage Capacity Planning + +In Apache Ozone, managing disk capacity is critical for maintaining high availability. Ozone uses a multi-layered approach to ensure that Datanodes do not run out of physical space, which could lead to data corruption or service hangs. + +For background on Datanode volumes and related settings, see [Datanodes](../../../core-concepts/architecture/datanodes). Full property descriptions are in the [configuration appendix](../appendix). + +## When is a Disk Considered "Full"? + +A disk (or "Volume" in Ozone terminology) is considered **Full** for new data allocations and replication targets when the available physical space falls below a specific threshold. + +This threshold is the sum of two "Reserved Space" configurations plus a safety buffer for the operation itself: + +`Failure Threshold = (Volume Min Free Space) + (DU Reserved Space) + (Operation Buffer)` + +If a volume's free space is less than this threshold, SCM will stop selecting this volume for new containers or as a destination for re-replication (including decommission and maintenance moves). + +## Reserved Space Concepts + +Ozone provides two types of reserved space to protect the system: + +### 1. Volume Min Free Space + +This is a safety margin managed by the Datanode to prevent the disk from ever reaching 100% capacity. It is the most important setting for capacity planning. + +- **Purpose**: Protects the Datanode from OS-level disk-full errors. +- **Configuration**: + - `hdds.datanode.volume.min.free.space`: A fixed value (e.g., `20GB`). Review Comment: Ah yes. I missed these recent additions. -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
