Greetings, Inherited a small Cassandra cluster with some repair issues and need some advice on recommended next steps. Apologies in advance for a long email.
Issue: Intermittent repair failures on two non-system keyspaces. - platform_users - platform_management Repair Type: Full, parallel repairs are run on each of the three nodes every five days. Repair command output for a typical failure: [2019-10-18 00:22:09,109] Starting repair command #46, repairing keyspace platform_users with repair options (parallelism: parallel, primary range: false, incremental: false, job threads: 1, ColumnFamilies: [], dataCenters: [], hosts: [], # of ranges: 12) [2019-10-18 00:22:09,242] Repair session 5282be70-f13d-11e9-9b4e-7f6db768ba9a for range [(-1890954128429545684,2847510199483651721], (8249813014782655320,-8746483007209345011], (4299912178579297893,6811748355903297393], (-8746483007209345011,-8628999431140554276], (-5865769407232506956,-4746990901966533744], (-4470950459111056725,-1890954128429545684], (4001531392883953257,4299912178579297893], (6811748355903297393,6878104809564599690], (6878104809564599690,8249813014782655320], (-4746990901966533744,-4470950459111056725], (-8628999431140554276,-5865769407232506956], (2847510199483651721,4001531392883953257]] failed with error [repair #5282be70-f13d-11e9-9b4e-7f6db768ba9a on platform_users/access_tokens_v2, [(-1890954128429545684,2847510199483651721], (8249813014782655320,-8746483007209345011], (4299912178579297893,6811748355903297393], (-8746483007209345011,-8628999431140554276], (-5865769407232506956,-4746990901966533744], (-4470950459111056725,-1890954128429545684], (4001531392883953257,4299912178579297893], (6811748355903297393,6878104809564599690], (6878104809564599690,8249813014782655320], (-4746990901966533744,-4470950459111056725], (-8628999431140554276,-5865769407232506956], (2847510199483651721,4001531392883953257]]] Validation failed in /10.x.x.x (progress: 26%) [2019-10-18 00:22:09,246] Some repair failed [2019-10-18 00:22:09,248] Repair command #46 finished in 0 seconds Additional Notes: Repairs encounter above failures more often than not. Sometimes on one node only, though occasionally on two. Sometimes just one of the two keyspaces, sometimes both. Apparently the previous repair schedule for this cluster included incremental repairs (script alternated between incremental and full repairs). After reading this TLP article: https://thelastpickle.com/blog/2017/12/14/should-you-use-incremental-repair.html the repair script was replaced with cassandra-reaper (v1.4.0), which was run with its default configs. Reaper was fine but only obscured the ongoing issues (it did not resolve them) and complicated the debugging process and so was then removed. The current repair schedule is as described above under Repair Type. Attempts at Resolution: (1) nodetool scrub was attempted on the offending keyspaces/tables to no effect. (2) sstablescrub has not been attempted due to the current design of the Docker image that runs Cassandra in each Kubernetes pod - i.e. there is no way to stop the server to run this utility without killing the only pid running in the container. Related Error: Not sure if this is related, though sometimes, when either: (a) Running nodetool snapshot, or (b) Rolling a pod that runs a Cassandra node, which calls nodetool drain prior shutdown, the following error is thrown: -- StackTrace -- java.lang.RuntimeException: Last written key DecoratedKey(10df3ba1-6eb2-4c8e-bddd-c0c7af586bda, 10df3ba16eb24c8ebdddc0c7af586bda) >= current key DecoratedKey(00000000-0000-0000-0000-000000000000, 17343121887f480c9ba87c0e32206b74) writing into /cassandra_data/data/platform_management/device_by_tenant_v2-e91529202ccf11e7ab96d5693708c583/.device_by_tenant_tags_idx/mb-45-big-Data.db at org.apache.cassandra.io.sstable.format.big.BigTableWriter.beforeAppend(BigTableWriter.java:114) at org.apache.cassandra.io.sstable.format.big.BigTableWriter.append(BigTableWriter.java:153) at org.apache.cassandra.io.sstable.SimpleSSTableMultiWriter.append(SimpleSSTableMultiWriter.java:48) at org.apache.cassandra.db.Memtable$FlushRunnable.writeSortedContents(Memtable.java:441) at org.apache.cassandra.db.Memtable$FlushRunnable.call(Memtable.java:477) at org.apache.cassandra.db.Memtable$FlushRunnable.call(Memtable.java:363) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748) Here are some details on the environment and configs in the event that something is relevant. Environment: Kubernetes Environment Config: Stateful set of 3 replicas Storage: Persistent Volumes Storage Class: SSD Node OS: Container-Optimized OS Container OS: Ubuntu 16.04.3 LTS Version: Cassandra 3.7 Data Centers: 1 Racks: 3 (one per zone) Nodes: 3 Tokens: 4 Replication Factor: 3 Replication Strategy: NetworkTopologyStrategy (all keyspaces) Compaction Strategy: STCS (all tables) Read/Write Requirements: Blend of both Data Load: <1GB per node gc_grace_seconds: default (10 days - all tables) Memory: 4Gi per node CPU: 3.5 per node (3500m) Java Version: 1.8.0_144 Heap Settings: -XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -XX:MaxRAMFraction=2 GC Settings: (CMS) -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=1 -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSInitiatingOccupancyOnly -XX:CMSWaitDuration=30000 -XX:+CMSParallelInitialMarkEnabled -XX:+CMSEdenChunksRecordAlways Any ideas are much appreciated.
