Deep storage is where segments are stored. It is a storage mechanism that Apache Druid does not provide. This deep storage infrastructure defines the level of durability of your data, as long as Druid processes can see this storage infrastructure and get at the segments stored on it, you will not lose data no matter how many Druid nodes you lose. If segments disappear from this storage layer, then you will lose whatever data those segments represented.
Local storage is intended for use in the following situations:
- You have just one server.
- Or, you have multiple servers, and they all have access to a shared filesystem (for example: NFS).
In multi-server production clusters, rather than local storage with a shared filesystem, it is instead recommended to use cloud-based deep storage (Amazon S3, Google Cloud Storage, or Azure Blob Storage), S3-compatible storage (like Minio), or HDFS. These options are generally more convenient, more scalable, and more robust than setting up a shared filesystem.
The following configurations in
common.runtime.properties apply to local storage:
|Must be set.|
|any local directory||Directory for storing segments. Must be different from |
|Whether segments in |
druid.storage.storageDirectory must be set to a different path than
Amazon S3 or S3-compatible
Google Cloud Storage
Azure Blob Storage
See druid-hdfs-storage extension documentation.
For additional deep storage options, please see our extensions list.