Hi, After upgrading to Ceph 16.2.14 we had several OSD crashes in bstore_kv_sync thread: 1. "assert_thread_name": "bstore_kv_sync", 2. "backtrace": [ 3. "/lib64/libpthread.so.0(+0x12cf0) [0x7ff2f6750cf0]", 4. "gsignal()", 5. "abort()", 6. "(ceph::__ceph_assert_fail(char const*, char const*, int, char const*)+0x1a9) [0x564dc5f87d0b]", 7. "/usr/bin/ceph-osd(+0x584ed4) [0x564dc5f87ed4]", 8. "(RocksDBBlueFSVolumeSelector::sub_usage(void*, bluefs_fnode_t const&)+0x15e) [0x564dc6604a9e]", 9. "(BlueFS::_flush_range_F(BlueFS::FileWriter*, unsigned long, unsigned long)+0x77d) [0x564dc66951cd]", 10. "(BlueFS::_flush_F(BlueFS::FileWriter*, bool, bool*)+0x90) [0x564dc6695670]", 11. "(BlueFS::fsync(BlueFS::FileWriter*)+0x18b) [0x564dc66b1a6b]", 12. "(BlueRocksWritableFile::Sync()+0x18) [0x564dc66c1768]", 13. "(rocksdb::LegacyWritableFileWrapper::Sync(rocksdb::IOOptions const&, rocksdb::IODebugContext*)+0x1f) [0x564dc6b6496f]", 14. "(rocksdb::WritableFileWriter::SyncInternal(bool)+0x402) [0x564dc6c761c2]", 15. "(rocksdb::WritableFileWriter::Sync(bool)+0x88) [0x564dc6c77808]", 16. "(rocksdb::DBImpl::WriteToWAL(rocksdb::WriteThread::WriteGroup const&, rocksdb::log::Writer*, unsigned long*, bool, bool, unsigned long)+0x309) [0x564dc6b780c9]", 17. "(rocksdb::DBImpl::WriteImpl(rocksdb::WriteOptions const&, rocksdb::WriteBatch*, rocksdb::WriteCallback*, unsigned long*, unsigned long, bool, unsigned long*, unsigned long, rocksdb::PreReleaseCallback*)+0x2629) [0x564dc6b80c69]", 18. "(rocksdb::DBImpl::Write(rocksdb::WriteOptions const&, rocksdb::WriteBatch*)+0x21) [0x564dc6b80e61]", 19. "(RocksDBStore::submit_common(rocksdb::WriteOptions&, std::shared_ptr<KeyValueDB::TransactionImpl>)+0x84) [0x564dc6b1f644]", 20. "(RocksDBStore::submit_transaction_sync(std::shared_ptr<KeyValueDB::TransactionImpl>)+0x9a) [0x564dc6b2004a]", 21. "(BlueStore::_kv_sync_thread()+0x30d8) [0x564dc6602ec8]", 22. "(BlueStore::KVSyncThread::entry()+0x11) [0x564dc662ab61]", 23. "/lib64/libpthread.so.0(+0x81ca) [0x7ff2f67461ca]", 24. "clone()" 25. ], I am attaching two instances of crash info for further reference: https://pastebin.com/E6myaHNU OSD configuration is rather simple and close to default: osd.6 dev bluestore_cache_size_hdd 4294967296 osd.6 dev bluestore_cache_size_ssd 4294967296 osd advanced debug_rocksdb 1/5 osd advanced osd_max_backfills 2 osd basic osd_memory_target 17179869184 osd advanced osd_recovery_max_active 2 osd advanced osd_scrub_sleep 0.100000 osd advanced rbd_balance_parent_reads false debug_rocksdb is a recent change, otherwise this configuration has been running without issues for months. The crashes happened on two different hosts with identical hardware, the hosts and storage (NVME DB/WAL, HDD block) don't exhibit any issues. We have not experienced such crashes with Ceph < 16.2.14. Is this a known issue, or should I open a bug report? Best regards, Zakhar