HowTo DR
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This document discusses disaster recovery (DR) planning and strategies for databases. It emphasizes the importance of having a complete DR plan that is tested regularly. The plan should address different types of disasters and limit downtime and data loss. Effective DR strategies include backups, replication, continuous backup, replacement procedures, and written recovery procedures. Plans should be tested quarterly and involve replacing failed servers, networks, storage and restoring from backups. Cloud-based DR also requires redundancy of services and rapid deployment of replacement instances.
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HowTo DR
- 1. HowTo DR Josh Berkus PostgreSQL Experts SCALE 2014
- 2. Disaster Recovery “The process, policies and procedures that are related to preparing for recovery or continuation of technology infrastructure which are vital to an organization after a natural or human-induced disaster.” Wikipedia, February 2014
- 3. Disaster Recovery Restoring services after the unexpected.
- 4. Disaster Recovery Limiting: 1. Downtime 2. Data Loss
- 5. Do you have a DR Plan?
- 8. Dilbert is a copyright of Scott Adams. Used here as parody. All rights reserved to Scott Adams.
- 9. Threat Model
- 13. Accepting Loss
- 14. The Nines Nines 99.9% 99.99% 99.999% Down/Year 9 hours 1 hour 5 minutes
- 15. The Nines ● Treats all downtime causes as identical – ● ● ● except the ones it ignores Doesn't address data loss Really “Business Continuity” also unrealistic
- 16. Disaster Server Failure Network Failure Admin Error Bad Update Storage Failure Getting Hacked Natural Disaster Downtime Data Loss Detect
- 17. Disaster Downtime Data Loss Server Failure 0 0 Network Failure 0 0 Admin Error 0 0 Bad Update 0 0 Storage Failure 0 0 Getting Hacked 0 0 Natural Disaster 0 0 Detect 10 yrs 10 yrs
- 19. Disaster Downtime Data Loss Server Failure 5min 1min Network Failure 3hrs 10min Admin Error 1hr 1hr Bad Update 1hr 1hr Storage Failure 5min 30min Getting Hacked 1hr 1hr Natural Disaster 6hrs 1hr Detect 3 mo 3 mo
- 20. Your DR Plan
- 21. Elements of a Plan 1. Backups/Replicas 2. Replacements 3. Procedures 4. People
- 24. Backups-● ● Slow to restore Data loss interval
- 25. Backups ● Good for: natural disaster – admin error, bad update – software bugs – getting hacked – ● Bad for everything else
- 26. Replication ● ● ● ● ● ● Postgres binary replication MySQL replication Redundant HBase nodes Redis clustering DRBD GlusterFS etc.
- 28. Replication-● ● ● ● ● Extra hardware Complex High-maintenance Can hurt performance Can replicate failures
- 29. Replication ● Good For: – ● server, storage, network failure Bad For: admin error, getting hacked – software bugs –
- 30. Continuous Backup ● ● ● Also “PITR” Continous like replication Partial recovery like backups
- 32. … where you gonna restore those backups to?
- 34. Procedures
- 36. 3AM is not the time to improvise
- 37. Procedures … for each recovery step … for deciding what steps
- 38. Database Server Does Not Respond 1. Determine if physical server is down a. if network is down, use plan N1. 2. If not, try to restart database using command … 3. Still down? Fail over to replica using command … 4. Check replica. 5. Not working? Restore backup to test server 1 using command ...
- 39. Good: detailed written procedures Better: written procedures with pastable commands Best: tested single-command scripts
- 40. Fallback Procedures ● ● ● Sometimes recovery fails Have fallback procedures If the fallback fails … time for a meeting!
- 43. Know who to call ● ● ● ● ● on call staff experts in each service consultants/contractors vendors required authorizations
- 44. Contact Book ● ● Include as much contact information as possible Put copies in more than one place – ● including paper! Keep it up to date
- 45. Test Your DR Good: when you create the procedure Better: quarterly Best: as part of daily/weekly provisioning
- 46. An untested backup is one which doesn't work.
- 47. DR in the Cloud
- 48. “It's a cloud, right? That means it's redundant, right?”
- 49. … not necessarily for your servers unless you pay for it!
- 50. Some new problems ● ● ● ● Instance failure Resource overcommit Zone failures Admin error at scale
- 51. Some new solutions ● Redundant services – ● ● RDS, VIP, S3 Rapid server deployment Cheap replicas
- 52. … otherwise pretty much the same.
- 53. backup locations ● shared instance storage (EBS) – ● fast failover for instance fail long-term storage API (S3) redundant – large –
- 54. Use your rapid deploy! ● ● Continuous backup to S3 Deploy scripts + server images – ● Chef/Salt/Puppet/etc. helps here = fast recovery – with low running costs
- 55. DR Tips ● Have multiple copies of your plan – ● ● in multiple locations A SAN is not a DR solution One form of backup is seldom enough
- 56. Questions? ● Josh Berkus www.databasesoup.com – www.pgexperts.com – ● Coming up: NYC pgDay April 3-4 – pgCon May 21-24 – Copyright 2013 PostgreSQL Experts Inc. Released under the Creative Commons Share-Alike 3.0 License. All images, logos and trademarks are the property of their respective owners and are used under principles of fair use unless otherwise noted.