Radim Vansa created ISPN-4949: --------------------------------- Summary: Split brain: data updated in degraded mode Key: ISPN-4949 URL: https://issues.jboss.org/browse/ISPN-4949 Project: Infinispan Issue Type: Feature Request Components: State Transfer Affects Versions: 7.0.0.Final Reporter: Radim Vansa Priority: Critical 1) cluster A, B, C, D splits into 2 parts: A, B (coord A) finds this out immediately and enters degraded mode with CH [A, B, C, D] C, D (coord D) first detects that B is lost, gets view A, C, D and starts rebalance with CH [A, C, D]. Segment X is primary owned by C (it had backup on B but this got lost) 2) D detects that A was lost as well, therefore enters degraded mode with CH [A, C, D] 3) C inserts entry into X: all owners (only C) is present, therefore the modification is allowed 4) cluster is merged and coordinator finds out that the oldest stable topology has CH [A, B, C, D] - logs 'No active or unavailable partitions, so all the partitions must be in degraded mode' (yes, all partitions are in degraded mode, but write has happened in the meantime) 5) The old CH is broadcast in newest topology, no rebalance happens 6) Inconsistency: read in X may miss the update -- This message was sent by Atlassian JIRA (v6.3.8#6338)