Advanced backup methods (Postgres@CERN)
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The document discusses advanced PostgreSQL backup and recovery methods, outlining the necessity of backups, different types of backup tools such as Barman, pgBackRest, pg_probackup, and wal-g, and their respective features. It highlights the importance of aspects like convenience, performance, incremental backups, and cloud support when selecting a backup tool. The document also includes detailed information about backup management, wal archive management, streaming backups, and restoring processes.
Advanced backup methods (Postgres@CERN)
- 1. Advanced PostgreSQL backup & recovery methods Anastasia Lubennikova Postgres@CERN 2020 1
- 2. Agenda - Why backup? - What is a good backup tool? - Overview of advanced backup features - Overview of PostgreSQL backup tools Spoiler: this talk doesn’t contain any benchmarks. 2
- 3. Why do you need a backup? - To restore the database after an accident - hardware failure - software bug - human error - To set up a new replica - To create a test environment - To inspect data from the past 3
- 4. What are the options? - replica is not a backup - dump a.k.a. “logical backup” - storage snapshots - pg_basebackup - set of custom scripts - PostgreSQL specific backup tools 4
- 5. What makes a good backup tool? - Convenience - out-of-box automatization of various routines - documentation & support - convenient and stable api - Performance - parallel execution - compression - incremental & differential backups - WAL prefetch 5
- 6. What backup tools exist? - Barman - pgBackRest - pg_probackup - WAL-G - BART - part of the “EDB Advanced Server” - requires pg_basebackup 6
- 7. Who is who? Barman - https://www.pgbarman.org/ - 2ndQuadrant - GPL v 3.0 - Python - first release: 2011 - Two methods: basebackup & rsync Notable features: Synchronous streaming for “zero data loss”. 7
- 8. Who is who? pgBackRest - https://pgbackrest.org/ - Crunchy Data - MIT License - C - first release: 2014 Notable features: Performance optimizations for large backups. 8
- 9. Who is who? pg_probackup - https://github.com/postgrespro/pg_probackup - Postgres Professional - PostgreSQL License - C - first release: 2017 (based on pg_arman) Notable features: Page-level incremental backups and built-in validation. 9
- 10. Who is who? WAL-G - https://github.com/wal-g/wal-g - introduced by Citus Data, now maintained by Yandex Cloud team - Apache License, Version 2.0 - Go - first release: 2017 ( “based on” WAL-E) Notable features: Out-of-box support for various cloud storages. 10
- 11. Feature list 1. Documentation & Support 2. Backup management 3. WAL archive management 4. Incremental backups 5. Compression and parallel execution 6. Remote backup 7. Cloud backup 8. Advanced restore options 9. Backup validation 10. Backup retention 11
- 12. 1. Documentation & Support 12
- 13. Documentation Barman User guide & command reference. Great overview of backup architectures pgBackRest User guide & command reference pg_probackup User guide & command reference WAL-G README 13
- 14. Installation Barman Linux packages, Build from source pgBackRest Linux packages, Build from source pg_probackup Linux packages, Build from source, Windows installer WAL-G Linux binary, Build from source 14
- 15. Support: bug fixes Barman https://github.com/2ndquadrant-it/barman/issues pgBackRest https://github.com/pgbackrest/pgbackrest/issues pg_probackup https://github.com/postgrespro/pg_probackup/issues WAL-G https://github.com/wal-g/wal-g/issues 15
- 16. Commercial support Barman 2ndQuadrant pgBackRest CrunchyData pg_probackup Postgres Professional WAL-G 16
- 18. Set up new PostgreSQL instance Barman server configuration files pgBackRest stanza configuration files pg_probackup instance configuration files, set-config command WAL-G - config via environment variables 18
- 19. Backup information Barman plain pgBackRest plain, json + postgresql table pg_probackup plain, json + detailed wal archive info WAL-G plain, json 19
- 20. 3. WAL archive management 20
- 21. WAL archive management Barman rsync / get-wal pgBackRest archive-push / archive get archive-async pg_probackup archive-push / archive-get WAL-G wal-push / wal-fetch wal prefetch 21
- 22. Streaming backups - Recovery Point Objective (RPO): "maximum targeted period in which data might be lost from an IT service due to a major incident" - “RPO = 0” (Zero data loss) can be achieved by synchronous WAL streaming - replication slot prevents the removal of WAL that is not yet received (PostgreSQL feature) 22
- 23. Streaming backups Barman streaming_archiver (pg_recievewal) replication slot pgBackRest pg_probackup backup --stream replication slot WAL-G 23
- 24. 4. Incremental backups Full backup includes all data files. Differential backup contains changes since last full backup. Incremental backup contains changes since last backup. 24
- 25. Incremental backup methods - DELTA - read everything, backup what changed - independent method - read load on data server - PAGE - scan WAL to determine changed blocks - requires WAL archive - minimal load on data server - PTRACK - remember changed blocks in a map - requires core patch - minimal load during backup 25
- 26. Incremental backups Barman file-level incremental (DELTA) pgBackRest file-level incremental (DELTA) file-level differential (DELTA) pg_probackup page-level incremental: DELTA, PAGE, PTRACK WAL-G page-level incremental (DELTA) 26
- 27. 5. Compression and parallel execution 27
- 28. 6. Remote backup Barman SSH pgBackRest SSH pg_probackup SSH WAL-G 28
- 30. Backup to cloud storage Barman scripts to ship backups to S3 pgBackRest Amazon S3 + encryption pg_probackup WAL-G Amazon S3, Google Cloud Storage, Azure Storage, Swift Object Storage + encryption 30
- 31. Extra backup features - Backup from standby (All tools) - to reduce load on master data server - Resume backup (only pgBackRest) 31
- 32. 8. Advanced restore options. PITR Restore to a certain moment in time. 32
- 33. Point-in-time-recovery Barman recovery target options pgBackRest recovery target options pg_probackup recovery target options WAL-G 33
- 34. Partial restore Barman pgBackRest restore selected databases pg_probackup restore selected databases WAL-G 34
- 36. Validate backups Barman DIY with custom hooks on backup & restore pgBackRest page checksums on backup pg_probackup page checksums on backup validate on demand check instance WAL-G 36
- 38. 10. Backup retention. Redundancy = 3 38
- 39. 10. Backup retention. Window = 7 days 39
- 40. Retention policy Barman retention_policy = REDUNDANCY retention_policy = RECOVERY WINDOW pgBackRest redundancy pg_probackup --retention-redundancy --retention-window WAL-G redundancy: retain N window: delete before 40
- 41. Backup pinning Barman pgBackRest pg_probackup ttl=0 WAL-G backup-mark 41
- 42. Archive retention Barman pgBackRest Archive Retention --repo-retention-archive pg_probackup delete --expired --wal --wal-depth=1 WAL-G 42
- 43. Backup merging Save space by merging old incremental backups. 43
- 45. 45
- 46. Conclusion Barman (rsync) pgBackRest pg_probackup WAL-G Support + + + + Backup management + + + - WAL management + + + + Incremental backup + + + + Compression & parallel execution + + + + 46
- 47. Conclusion Barman (rsync) pgBackRest pg_probackup WAL-G Remote backup + + + + Cloud backup - + - + Advanced restore + + + - Backup validation + + + - Backup retention + + + + 47