Backup & PITR
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Pigsty uses pgBackRest for PITR backup & restore.
In the case of a hardware failure, a physical replica failover could be the best choice. Whereas for data corruption scenarios (whether machine or human errors), Point-in-Time Recovery (PITR) is often more appropriate.
Backup
Use the following command to perform the backup:
# stanza name = {{ pg_cluster }} by default
pgbackrest --stanza=${stanza} --type=full|diff|incr backup
# you can also use the following command in pigsty (/pg/bin/pg-backup)
pg-backup # make a backup, incr, or full backup if necessary
pg-backup full # make a full backup
pg-backup diff # make a differential backup
pg-backup incr # make a incremental backup
Use the following command to print backup info:
pb info # print backup info
You can also acquire backup info from the monitoring system: PGCAT Instance - Backup
Backup Info Example
$ pb info
stanza: pg-meta
status: ok
cipher: none
db (current)
wal archive min/max (14): 000000010000000000000001/000000010000000000000023
full backup: 20221108-105325F
timestamp start/stop: 2022-11-08 10:53:25 / 2022-11-08 10:53:29
wal start/stop: 000000010000000000000004 / 000000010000000000000004
database size: 96.6MB, database backup size: 96.6MB
repo1: backup set size: 18.9MB, backup size: 18.9MB
incr backup: 20221108-105325F_20221108-105938I
timestamp start/stop: 2022-11-08 10:59:38 / 2022-11-08 10:59:41
wal start/stop: 00000001000000000000000F / 00000001000000000000000F
database size: 246.7MB, database backup size: 167.3MB
repo1: backup set size: 35.4MB, backup size: 20.4MB
backup reference list: 20221108-105325F
Restore
Use the following command to perform restore
pg-pitr # restore to wal archive stream end (e.g. used in case of entire DC failure)
pg-pitr -i # restore to the time of latest backup complete (not often used)
pg-pitr --time="2022-12-30 14:44:44+08" # restore to specific time point (in case of drop db, drop table)
pg-pitr --name="my-restore-point" # restore TO a named restore point create by pg_create_restore_point
pg-pitr --lsn="0/7C82CB8" -X # restore right BEFORE a LSN
pg-pitr --xid="1234567" -X -P # restore right BEFORE a specific transaction id, then promote
pg-pitr --backup=latest # restore to latest backup set
pg-pitr --backup=20221108-105325 # restore to a specific backup set, which can be checked with pgbackrest info
pg-pitr # pgbackrest --stanza=pg-meta restore
pg-pitr -i # pgbackrest --stanza=pg-meta --type=immediate restore
pg-pitr -t "2022-12-30 14:44:44+08" # pgbackrest --stanza=pg-meta --type=time --target="2022-12-30 14:44:44+08" restore
pg-pitr -n "my-restore-point" # pgbackrest --stanza=pg-meta --type=name --target=my-restore-point restore
pg-pitr -b 20221108-105325F # pgbackrest --stanza=pg-meta --type=name --set=20221230-120101F restore
pg-pitr -l "0/7C82CB8" -X # pgbackrest --stanza=pg-meta --type=lsn --target="0/7C82CB8" --target-exclusive restore
pg-pitr -x 1234567 -X -P # pgbackrest --stanza=pg-meta --type=xid --target="0/7C82CB8" --target-exclusive --target-action=promote restore
The pg-pitr
script will generate instructions for you to perform PITR.
For example, if you wish to rollback current cluster status back to "2023-02-07 12:38:00+08"
:
$ pg-pitr -t "2023-02-07 12:38:00+08"
pgbackrest --stanza=pg-meta --type=time --target='2023-02-07 12:38:00+08' restore
Perform time PITR on pg-meta
[1. Stop PostgreSQL] ===========================================
1.1 Pause Patroni (if there are any replicas)
$ pg pause <cls> # pause patroni auto failover
1.2 Shutdown Patroni
$ pt-stop # sudo systemctl stop patroni
1.3 Shutdown Postgres
$ pg-stop # pg_ctl -D /pg/data stop -m fast
[2. Perform PITR] ===========================================
2.1 Restore Backup
$ pgbackrest --stanza=pg-meta --type=time --target='2023-02-07 12:38:00+08' restore
2.2 Start PG to Replay WAL
$ pg-start # pg_ctl -D /pg/data start
2.3 Validate and Promote
- If database content is ok, promote it to finish recovery, otherwise goto 2.1
$ pg-promote # pg_ctl -D /pg/data promote
[3. Restart Patroni] ===========================================
3.1 Start Patroni
$ pt-start; # sudo systemctl start patroni
3.2 Enable Archive Again
$ psql -c 'ALTER SYSTEM SET archive_mode = on; SELECT pg_reload_conf();'
3.3 Restart Patroni
$ pt-restart # sudo systemctl start patroni
[4. Restore Cluster] ===========================================
3.1 Re-Init All Replicas (if any replicas)
$ pg reinit <cls> <ins>
3.2 Resume Patroni
$ pg resume <cls> # resume patroni auto failover
3.2 Make Full Backup (optional)
$ pg-backup full # pgbackrest --stanza=pg-meta backup --type=full
Policy
You can customize your backup policy with node_crontab
and pgbackrest_repo
- Schedule full or incr backup with
node_crontab
- setup backup retention policy with
pgbackrest_repo
local repo
For example, the default pg-meta
will take a full backup every day at 1 am.
node_crontab: # make a full backup 1 am everyday
- '00 01 * * * postgres /pg/bin/pg-backup full'
With the default local repo retention policy, it will keep at most two full backups and temporarily allow three during backup.
pgbackrest_repo: # pgbackrest repo: https://pgbackrest.org/configuration.html#section-repository
local: # default pgbackrest repo with local posix fs
path: /pg/backup # local backup directory, `/pg/backup` by default
retention_full_type: count # retention full backups by count
retention_full: 2 # keep 2, at most 3 full backup when using local fs repo
Your backup disk storage should be at least three x database file size + WAL archive in 3 days.
MinIO repo
When using MinIO, storage capacity is usually not a problem. You can keep backups as long as you want.
For example, the default pg-test
will take a full backup on Monday and incr backup on other weekdays.
node_crontab: # make a full backup 1 am everyday
- '00 01 * * 1 postgres /pg/bin/pg-backup full'
- '00 01 * * 2,3,4,5,6,7 postgres /pg/bin/pg-backup'
And with a 14-day time retention policy, backup in the last two weeks will be kept. But beware, this guarantees a week’s PITR period only.
pgbackrest_repo: # pgbackrest repo: https://pgbackrest.org/configuration.html#section-repository=
minio: # optional minio repo for pgbackrest
type: s3 # minio is s3-compatible, so s3 is used
s3_endpoint: sss.pigsty # minio endpoint domain name, `sss.pigsty` by default
s3_region: us-east-1 # minio region, us-east-1 by default, useless for minio
s3_bucket: pgsql # minio bucket name, `pgsql` by default
s3_key: pgbackrest # minio user access key for pgbackrest
s3_key_secret: S3User.Backup # minio user secret key for pgbackrest
s3_uri_style: path # use path style uri for minio rather than host style
path: /pgbackrest # minio backup path, default is `/pgbackrest`
storage_port: 9000 # minio port, 9000 by default
storage_ca_file: /etc/pki/ca.crt # minio ca file path, `/etc/pki/ca.crt` by default
bundle: y # bundle small files into a single file
cipher_type: aes-256-cbc # enable AES encryption for remote backup repo
cipher_pass: pgBackRest # AES encryption password, default is 'pgBackRest'
retention_full_type: time # retention full backup by time on minio repo
retention_full: 14 # keep full backup for last 14 days
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