[SERVER-85279] ARBITER constantly raises warnings due to missing local.oplog.rs Created: 17/Jan/24  Updated: 23/Jan/24

Status: Open
Project: Core Server
Component/s: None
Affects Version/s: 7.0.4
Fix Version/s: None

Type: Bug Priority: Major - P3
Reporter: Wernfried Domscheit Assignee: Backlog - Service Architecture
Resolution: Unresolved Votes: 0
Labels: arbiter, oplog
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Assigned Teams:
Service Arch
Operating System: ALL
Sprint: Service Arch Prioritized List
Participants:

 Description   

I recently updated to MongoDB version 7. I am using a sharded cluster with PSA (PRIMARY-SECONDARY-ARBITER) shards. The arbiter not is constantly writing every second this warning into to log:

{
  "t": {
    "$date": "2024-01-17T07:47:12.004+01:00"
  },
  "s": "W",
  "c": "QUERY",
  "id": 23799,
  "ctx": "ftdc",
  "msg": "Aggregate command executor error",
  "attr": {
    "error": {
      "code": 26,
      "codeName": "NamespaceNotFound",
      "errmsg": "Unable to retrieve storageStats in $collStats stage :: caused by :: Collection [local.oplog.rs] not found."
    },
    "stats": {},
    "cmd": {
      "aggregate": "oplog.rs",
      "cursor": {},
      "pipeline": [
        {
          "$collStats": {
            "storageStats": {
              "waitForLock": false,
              "numericOnly": true
            }
          }
        }
      ],
      "$db": "local"
    }
  }
} 

It does not have a big impact, because the ARBITER does not store any data. However, it is filling up the logfile, I get every day a logfile of 55MB.

I don't think a permanent warning should be part of a normally running mongod process



 Comments   
Comment by Chris Kelly [ 17/Jan/24 ]

Hi!

Thanks for your report. This appears to be being called internally via ftdc (diagnostic data capture) which is leveraging $collStats' output.

I'll pass this to the relevant team for a further look here.

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