Master Replica Lease Transfer in Distributed Systems
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Solution Overview
Problem
Existing distributed system technologies face challenges in efficiently transferring a master replica between master and slave replicas, particularly in ensuring the uniqueness of the master replica and minimizing the impact on service availability.
Innovation Solution
A method for lease transfer between master and slave replicas involves calculating an initial master replica lease, sending a lease establishment message, determining lease effectiveness, preparing for transfer, extending leases, and confirming the transfer, ensuring the uniqueness and efficient transfer of the master replica.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional election solutions are used to elect a master replica, then service availability is ensured through master/slave disaster recovery, but the transfer process is time-consuming and impacts service availability when master replica location adjustment is needed
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-establishing leases for potential master replicas before transfer is needed. Slave replicas maintain pre-computed lease information in advance, so when a master replica transfer is required, the system can immediately activate a pre-prepared candidate rather than performing a time-consuming election process. This resolves the contradiction by preparing transfer candidates beforehand, reducing transfer time while maintaining service availability through the pre-validated lease mechanism.
2Reliability
If a full election process is performed for master replica transfer, then uniqueness of the new master replica is ensured, but the transfer impact on service availability increases and efficiency decreases
Solution Approach 1:
The patent extracts the essential uniqueness guarantee mechanism from the full election process. Instead of performing a complete election procedure, the system only extracts and utilizes the lease calculation and validation components. Slave replicas pre-calculate leases independently, and the system only needs to validate lease uniqueness and establish the master-slave relationship, eliminating the time-consuming consensus and voting steps of a full election while preserving the uniqueness guarantee through lease validation.
Solution Approach 2:
The patent applies preliminary action by having slave replicas pre-calculate their lease values and prepare transfer candidate information before any transfer event occurs. This pre-computation includes determining lease duration, validity conditions, and candidate suitability. When transfer is needed, these pre-prepared elements are immediately validated and activated, ensuring uniqueness through the pre-computed lease mechanism while dramatically improving transfer efficiency compared to performing a complete election process at transfer time.
3Duration of action of stationary object
If the master replica lease is extended to remaining slave replicators, then service continuity is maintained, but the complexity of lease management increases
Solution Approach 1:
The patent applies preliminary action by having the target replicator (new master) pre-calculate its lease information before the actual transfer occurs. This pre-computed lease data includes validity period, scope, and conditions. When the transfer is executed, the current master replicator simply extends the lease to remaining slave replicators using this pre-prepared information, rather than calculating and negotiating lease terms in real-time. This reduces the complexity of lease management during the critical transfer moment while ensuring service continuity through the pre-validated lease extension.
Data Source
AI summary
Lease transfer between master and slave replicas is described. A master replicator determines that an initial master replica lease takes effect. On determining that a master replica transfer needs to be performed, sending a transfer preparation message to a target replicator prior to expiration of a current master replica lease. The target replicator locally starts and calculates a new master replica lease and returns a readiness response to the master replicator. The master replicator sends a lease extension message to remaining slave replicators to extend local corresponding leases. After receiving lease extension success responses of a majority of the slave replicators, the master replicator terminates the local master replica lease of the master replicator in advance, and sends a transfer confirmation message to the target replicator. The target replicator validates the new master replica lease to make the target replicator a new master replicator.