Read

TODO: File a subtask under HDDS-9862 and complete this page or section.

Reading Metadata

Reading Data

Trace every part of a read request from beginning to end. This includes:

• Client getting encryption keys

• Client calling OM to create key

• OM validating client's Kerberos principal

• OM checking permissions (Ranger or Native ACLs)

• OM generating block tokens from the shared secret previously retrieved from SCM

• OM getting block locations from SCM or from its cache.

• OM returning container, blocks, pipeline, block tokens

• Client sending block tokens and Datanode validating based on the shared secret from SCM

• Client sending read chunk requests to Datanode to fetch the data.

  • For replication:

    • Include topology choices of which Datanodes to use
    • Include failover handling

  • For EC, link to the EC feature page.

• Client validating checksums