INT 21h

Hi, I am Vladimir Smagin, SysAdmin and Kaptain. Telegram Email / GIT / Микроблог / Thingiverse / RSS / GPG

История провала: webdav и nginx для Windows

№ 10985. В разделе " Sysadmin " от April 25th, 2020

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How to move snap application between computers with snapshots

№ 10960. В разделе " Sysadmin " от March 29th, 2020

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wal-g and Postgresql

№ 10938 В разделе "Sysadmin" от March 20th, 2020,
В подшивках: , ,

Initials

Master database: postgresql-10, in production
Backup storage: minio with empty pg-walg-backup bucket

Task: Create slave postgresql-10 server with recovery

Preparing for both servers

Install wal-g binary manually or use my Ubuntu repository (install walg-lzo).

Create special script for wal-g with variables, save to /var/lib/postgresql/walg-postgresql

#!/bin/bash
source /etc/profile

export AWS_ENDPOINT=http://minio.myserv.com:9000
export AWS_ACCESS_KEY_ID="KEYNAMEKEYNAMEKEYNAME"
export AWS_SECRET_ACCESS_KEY="SECRETSECRETSECRETSECRETSECRETSECRET"
export WALE_S3_PREFIX="s3://pg-walg-backup/"
export AWS_S3_FORCE_PATH_STYLE="true"
export AWS_REGION=us-east-1
export PGHOST=/var/run/postgresql
export PGUSER=postgres
export PGPORT=5433

wal-g $@

It is not secure to store this file global readable. Best choice to place it in postgres home directory without read by others:

chmod 500 /var/lib/postgresql/walg-postgresql
chown postgres:postgres /var/lib/postgresql/walg-postgresql

Master server

Add to postgresql.conf:

archive_mode = on
archive_command = '/var/lib/postgresql/walg-postgresql wal-push %p'

Ok, now run backup-push to create full backup:

/var/lib/postgresql/walg-postgresql backup-push /pg_data/10/main

Slave server

Stop postgresql and remove data directory, wal-g requires empty directory before restore.

Now run:

/var/lib/postgresql/walg-postgresql backup-fetch /pgdata/10/main LATEST

Create /pgdata/10/main/recovery.conf:

standby_mode = 'on'
restore_command = 'walg-postgresql wal-fetch "%f" "%p"'

Now see logfile for wal restoring, database in recovery mode.

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Postgresql logical backup failed, pg_dump said: PQgetResult() failed

№ 10947 В разделе "Sysadmin" от March 20th, 2020,
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You made streaming backups and restoring with walg and now trying to make logical backups.

But some shit ruined your plans:

pg_dump: Dumping the contents of table "<table>" failed: PQgetResult() failed.

Many sites suggests to enable hot_standby_feedback in postgresql.conf, but actually you need also increase max_standby_archive_delay and max_standby_streaming_delay. I set 1 hour.

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Midnight Commander (mc) golden color scheme

№ 10915 В разделе "Sysadmin" от February 16th, 2020,
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My own color scheme for Midnight Commander. Nicely looks only on dark backgrounds and much better with transparent backgrounds.

Installation:

  • Add line export TERM=xterm-256color to the end of ~/.bashrc in your home directory
  • Place slut.ini to home directory ~/.local/share/mc/skins/slut.ini or /usr/share/mc/skins to be system-wide

Download slut.ini

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