Cases3 cases

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1. IL-0527 OpenStreetMap.org made no replication diffs for 16 hours as PostgreSQL logical decoding failed on a memory alloc error

   OpenStreetMap Foundation2025

   Symptoms

   At 21:40 UTC on 25 June 2025, Alertmanager alerted the OpenStreetMap operations team: minutely replication feed delayed - 6m 2s. Since 21:33 UTC every run of the osmdbt timer that produces the minutely replication diffs had failed with ERROR: invalid memory alloc request size 1243650064.

   Replication lag

   Root cause

   Software defect

   Component

   Database replicationDatabase

   Contributing factor

   Pages not delivered

   Detection

   Alertmanager sent the first alert at 21:40 UTC, minutely replication feed delayed - 6m 2s, and several more followed, but none was a pager or SMS alert. A community report followed at 00:37 UTC and a social media report at 01:13 UTC.

   Remediation

   • Stopped the osmdbt timer
   • Put OpenStreetMap.org into a read-only maintenance window to suppress edits
   • Ran osmdbt by hand with fakelog to skip ahead of the PostgreSQL replication condition
   • Restarted the osmdbt timer for minutely diffs
   • Ended the read-only maintenance window

   Action items

   • Upgrade PostgreSQL to 17.x
   • Raise an issue with the PostgreSQL developers

   Lessons

   Communication with the osmdbt developer was crucial for working out the workaround, and the operations team's understanding of osmdbt was limited.

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2. IL-0526 OpenStreetMap.org went offline, then read-only, for 56 hours after HE.net routing equipment cut both fibre uplinks

   OpenStreetMap Foundation2024

   Symptoms

   At 04:01 UTC on 15 December 2024, StatusCake monitoring sent SMS alerts that OpenStreetMap.org was unreachable. The website and the mapping API had gone completely offline at 03:53 UTC.

   Network unreachableService outage

   Trigger

   HE.net's routing equipment in Amsterdam failed at 03:53 UTC on 15 December 2024.

   Root cause

   Dependency failure

   Component

   ISP and transit networksDatabase replication

   Contributing factor

   Single point of failureNo runbook

   Detection

   StatusCake monitoring detected the outage at 04:01 UTC and sent SMS alerts, and the incident was reported to the operations team at once.

   Remediation

   • Activated a read-only backup instance of OpenStreetMap.org in Dublin
   • Brought a new Equinix Internet link into service in Amsterdam, bypassing HE.net and restoring full functionality
   • HE.net replaced its routing hardware and restored its service, and routing through HE.net resumed

   Action items

   • Move to a multi-ISP architecture so another provider can take over when one fails
   • Research backup ISPs for the Amsterdam servers, including BGP and keeping HE.net as a fallback
   • Add deeper route and latency monitoring and an automated escalation protocol
   • Hold failover drills for switching between ISPs and keep replication up to date
   • Agree SLAs with HE.net and Equinix Internet with defined escalation procedures and response times
   • Prepare the 4G out-of-band system as a manual fallback uplink that can sync Postgres replication data, and upgrade its hardware
   • Document outage communication procedures and delegate communication during outages
   • Investigate decoupling the OAuth service so authentication keeps working while the database is read-only

   Lessons

   Relying on HE.net alone left the Amsterdam servers with a single point of failure, so OpenStreetMap will keep multiple upstream providers. The 4G out-of-band link proved invaluable and should be able to carry data synchronisation. Resumed replication would have restored editing faster than the read-only backup. Frequent contact with the ISP gave no useful estimates, so the SLA needs to be better understood. Alerting on upstream connectivity needs refining, and a read-only OpenStreetMap.org also blocked logins to services that were not affected, because it could not save new tokens.

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3. IL-0525 OpenStreetMap.org went offline for 7h 27m when its uplink switch lost power during a data-centre power feed maintenance

   OpenStreetMap Foundation2022

   Symptoms

   From 20:18 UTC on 11 June 2022, OpenStreetMap.org was unavailable: all of its services hosted in Amsterdam, including www, the API, the wiki and planet, had no connectivity to the Internet. The outage began 18 minutes into Equinix's planned maintenance of power feed A at the Amsterdam data centre.

   Network unreachableService outage

   Trigger

   Equinix's planned 5-year maintenance of power feed A in Amsterdam, which started at 20:00 UTC on 11 June 2022.

   Root cause

   Hardware failure

   Component

   Network switchData center power and cooling

   Contributing factor

   Single point of failureLimited debug accessMonitoring blind spot

   Remediation

   • Waited for the end of the Equinix power feed A maintenance window instead of failing over to Dublin or moving the uplink; connectivity returned at 03:45 UTC

   Action items

   • Acknowledge ongoing outages faster
   • Add monitoring and alerting of switch PSU and FAN states
   • Replace the Cisco SG550X-48 switches and the Redundant Power System with Juniper EX4300 switches with redundant power supplies
   • Install out-of-band access equipment with dual power feeds in Amsterdam
   • Install redundant uplinks
   • Make site failover easier, less manual and lower risk
   • Introduce an on-call pager system for the operations SRE
   • Expand the SRE team
   • Continue and formalise fail-over tests for power, network, upstream link and service outages

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