# Large Follower Resolved-TS Gap Caused by Stale Peers

Source note: adapted from the Feishu `Storage oncall handbook` <https://pingcap.feishu.cn/wiki/RNzIwCexFiA1uXkRCvzcsIocnVb> and normalized into the transaction handbook.

- Phenomenon:
  - The maximum follower resolved-ts gap becomes unusually large.
  - Logs may show `leader missing`, while the corresponding region is absent in PD.
- Trigger / Preconditions:
  - A stale peer remains on a TiKV node after the region is no longer present in PD metadata.
- Key logs:
  - `leader missing`
- Key metrics:
  - Follower resolved-ts gap increases noticeably.
- Root cause:
  - The stale peer still participates in follower resolved-ts accounting even though PD no longer considers it part of a live region layout.
- Workaround:
  - Keep the stale peer as-is if it does not create additional impact.
  - If cleanup is needed, remove the stale region replica with `tikv-ctl tombstone`.
- Fixed version:
  - No fixed version is documented in the source material.
- Related oncall:
  - v6.5.9 the max gap of follower resolved-ts became large `ONCALL-7019`