| 摘要 |
PROBLEM TO BE SOLVED: To increase the availability of a system for holding a database with one of three or more database devices as a master and the others as slaves, when the master fails. SOLUTION: When the master fails, the slave database device 10A obtains a database log update number "L" and its own ID "I" from a storage part (S301), and generates a proposal number (L, I) for identifying a notification of candidacy for a new master and sends a candidacy notification Prepare(L, I) to the other slave database devices 10B and 10C (S302). The other slaves each obtain their own database log update number "L'" and their own ID "I'" from their own storage part to generate their own proposal number (L', I'), and if the received (L, I) is not smaller than their own (L', I'), send an acknowledgment notification PrepareACK (L, I). The slave that has the proposal number of a majority of acknowledgment notifications becomes a candidate for a new master. COPYRIGHT: (C)2011,JPO&INPIT
|
