[BOOKKEEPER-208] Separate write quorum from ack quorum

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.2.0
• Component/s: bookkeeper-client
• Assignee: Ivan Kelly
• Reporter: Flavio Paiva Junqueira
• Created: 04/Apr/12 15:34
• Updated: 13/Feb/13 15:46
• Resolved: 12/Sep/12 10:09

Description

There are use cases for bookkeeper that may require submitting add requests to a write set and returning upon receiving a confirmation from an ack set. The ack set must be a subset of the write set. An important special case is writing to all and returning upon hearing from a majority. Another important use case is avoiding s slow disks by writing to f + s + 1 and returning upon receiving f + 1 responses.

Currently, the write set and the ack set are the same for a ledger. Internal changes to support these cases include changes to LedgerHandle and PendingAddOp. We also need to add a call to the client API to accept different sizes for the write set and the ack set upon ledger creation.

It is also open for the discussion the need to implement a new distribution schedule. So far it looks like we can reuse the round robin implementation we currently have. We would need to implement a new one if, for example, the initial bookie of an add operation must be always the same.

Issue Links

• is related to: BOOKKEEPER-399 Let hub server configure write quorum and ack quorum.
• relates to: BOOKKEEPER-336 bookie readEntries is taking more time if the ensemble has failed bookie(s)