Page History

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• RLM Leader Task
  • It checks for rolled over LogSegments (which have the last message offset less than last stable offset of that topic partition) and copies them along with their offset/time/transaction indexes and leader epoch cache to the remote tier. It also serves the fetch requests for older data from the remote tier. Local logs are not cleaned up till those segments are copied successfully to remote even though their retention time/size is reached.

[We proposed an approach to creating a RemoteLogSegmentIndex, per topic-partition to track remote LogSegments. These indexes are described in more detail here. This allows having a larger index interval of remote log segments instead of a large number of small index files. It also supports encrypted segments by encrypting individual record batch and build the respective indexes. We may want to explore this approach by enhancing RemoteStorageManager in later versions ]

• RLM Follower Task 
  • It keeps track of the segments and index files on remote tier by looking into RemoteLogMetdataManager. RLM follower can also serve reading old data from the remote tier.

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Below are the leader topic partition's log offsets

Lx  = Local log start offset           L_z  = Local log end offset            L_y  = Last stable offset(LSO)

R_y  = Remote log end offset       R_x  = Remote log start offset

Lz >= Ly >= Lx and Ly >= Ry >= Rx

Manage Remote Log Segments

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