Atomic Test And Set Of Disk Block Returned False For Equality ((exclusive)) Jun 2026

: High I/O latency or intermittent connectivity issues can cause these "heartbeat" failures, leading to the host losing access to the volume. Common Symptoms

10-node Ceph cluster, BlueStore backend, NVMe-over-Fabrics. Error: OSD logs repeated: bluestore/StupidAllocator.cc: atomic test and set of disk block 0x4a20b returned false for equality . Root cause: A network partition caused two OSDs to believe they held the same allocation bitmap lock. The storage array (NVMe target) correctly rejected the second OSD’s compare-and-write. Fix: Reduced osd_heartbeat_grace from 20s to 5s, enabled faster fencing, and implemented retry logic with jitter. : High I/O latency or intermittent connectivity issues

To minimize the risk of encountering this error, consider the following best practices: enabled faster fencing