SmartData 2.6.x is supported in EMR V3.26.3 and later. This SmartData version delivers new features and optimized performance. For example, Tablestore and Raft instances can be used as the metadata storage backends of Namespace Service. Namespace Service can be deployed in high availability (HA) mode. The cache mode, block storage mode, and read/write performance of JindoFS are optimized.
New metadata storage methods
In earlier versions, you can use only RocksDB as a metadata storage backend. In SmartData 2.6.x, you can also use Tablestore or Raft instances as metadata storage backends. JindoFS achieves complete cloud-native storage with metadata stored in Tablestore or Raft instances and data stored in OSS buckets. Storage modules are independent of EMR clusters. This facilitates data restoration when you re-create a cluster. You can delete a cluster anytime. If Tablestore or Raft instances are used, you can deploy Namespace Service in HA mode. RocksDB is still a simple and efficient metadata storage method for scenarios that do not require Namespace Service in HA mode or high performance of metadata storage. For example, when you use JindoFS in cache mode, we recommend that you use RocksDB to store metadata.
Optimization of JindoFS usage modes
JindoFS supports the block storage mode and cache mode.
- The usage of the block storage mode is the same as that in versions earlier than EMR V3.26.3. For more information, see Use JindoFS in block storage mode.
- In cache mode, you can use the same method to access files as in block storage mode. You can also use the original file access method of OSS. For more information, see Use JindoFS in cache mode.
To use JindoFS in block storage mode, you must be granted permissions on files. If you do not have permissions on a file, you are not allowed to read or write data from or to the file. You can run UNIX commands or use Ranger to manage permissions. UNIX allows you to grant the rwxrwxrwx permission on files. Ranger allows you to configure complex permissions. For example, you can use wildcards in paths when you configure a permission. For more information about permissions, see Manage JindoFS permissions.