GMD can recover from most network failures, but there are a few scenarios to be aware of when using GMD:
- If a sending process crashes before an outgoing message can be completely saved to the GMD area, the message cannot be recovered.
- If a receiving process crashes after processing a message but before the highest sequence number can be updated in the GMD area, the message can potentially be processed twice.
- Mixing GMD and message priorities can cause the highest sequence number in the GMD area to be updated in non-sequential order. If the receiving process crashes while processing messages in non-increasing sequence number order, the resent messages can potentially be skipped.
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It is highly recommended that all GMD messages sent from the same publisher have the same priority setting, or they can be read out of order. Messages read out of order can result in message loss.
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These conditions are very unlikely, but can happen if a node or disk crashes at exactly the wrong time.