Patent ID: 8595546
Filing Date: 2013-11-26
Classification: G06F

Abstract:
1. A method for replicating states synchronously to provide for failover between nodes comprising machines of a high availability cluster serving at least one network client, said method comprising: a) identifying a number m of master candidates among said machines, where said number m is at least two; b) identifying a number n of quorum machines among said machines, where said number n is at least three and is odd; c) synchronously updating each of said m master candidates to maintain a current state; d) electing a current master from said number m of master candidates through a quorum-based majority vote among said quorum machines; e) issuing a current time-limited lease to said current master, said current timed-limited lease to be measured off by a local clock belonging to said current master, said current master running a service requested by said at least one network client while holding said current time-limited lease; f) bounding a relative clock skew of said current time-limited lease to an upper bound; wherein a failure of said current master triggers failover to a new master from among said number m of master candidates and issuance of a new time-limited lease to said new master, thereby preventing split brain situations between said master candidates.