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Incidents/2022-06-01 Lost index in cloudelastic

From Wikitech

document status: in-review


Incident metadata (see Incident Scorecard)
Incident ID 2022-06-01 Lost index in cloudelastic Start 2022-05-31 13:00 UTC
Task T309648 End 2022-07-12 14:00 UTC
People paged 0 Responder count 3
Coordinators Brian King Affected metrics/SLOs To the best of my knowledge, no SLOs affected
Impact For 41 days, Cloudelastic was missing search results about files from commons.wikimedia.org.

During a reimage operation, the cloudelastic Elasticsearch cluster lost a shard and went into red status, indicating data loss.

Until the data was restored, search results were incomplete on Cloudelastic. Restoration from production snapshots, using the previously understood and documented process, failed consistently, requiring a different approach to be devised which is why restoration was delayed by a month. Restoration was completed on 12 July.



  • Restore data to cloudelastic
  • Document cloudelastic cluster (what is its purpose, who are the stakeholders, etc)
  • Document restore process
  • Review monitoring for cloudelastic
  • Inform stakeholders of the current situation

TODO: Add the #Sustainability (Incident Followup) and the #SRE-OnFIRE (Pending Review & Scorecard) Phabricator tag to these tasks.


Incident Engagement ScoreCard
Question Answer


People Were the people responding to this incident sufficiently different than the previous five incidents?
Were the people who responded prepared enough to respond effectively
Were fewer than five people paged?
Were pages routed to the correct sub-team(s)?
Were pages routed to online (business hours) engineers? Answer “no” if engineers were paged after business hours.
Process Was the incident status section actively updated during the incident?
Was the public status page updated?
Is there a phabricator task for the incident?
Are the documented action items assigned?
Is this incident sufficiently different from earlier incidents so as not to be a repeat occurrence?
Tooling To the best of your knowledge was the open task queue free of any tasks that would have prevented this incident? Answer “no” if there are

open tasks that would prevent this incident or make mitigation easier if implemented.

Were the people responding able to communicate effectively during the incident with the existing tooling?
Did existing monitoring notify the initial responders?
Were all engineering tools required available and in service?
Was there a runbook for all known issues present?
Total score (count of all “yes” answers above)