MySQL / MariaDB backups to a NAS

Dump every database to its own compressed file, keep a few days, and fail loudly when something is wrong.

Requirements

• mysqldump or mariadb-dump. Newer MariaDB installs may only have mariadb-dump, so detect which one exists.
• gzip.
• A stored login for root (see Store MySQL backup credentials safely).
• A mounted backup share, for example /mnt/backup.

The core loop

DUMP=$(command -v mysqldump || command -v mariadb-dump) || exit 1
CLI=$(command -v mysql || command -v mariadb) || exit 1
mountpoint -q /mnt/backup || { logger -t mysql-backup "backup share not mounted"; exit 1; }

dbs=$("$CLI" -N -e 'SHOW DATABASES') || { logger -t mysql-backup "cannot connect"; exit 1; }
for db in $dbs; do
  case $db in information_schema|performance_schema|sys) continue;; esac
  "$DUMP" --single-transaction --routines --triggers --complete-insert "$db" \
    | gzip > "/mnt/backup/$(hostname -s)/$(date +%Y.%m.%d_%H).$db.sql.gz" \
    || logger -t mysql-backup "dump of $db failed"
done
find "/mnt/backup/$(hostname -s)" -maxdepth 1 -type f -name '*.sql.gz' -mtime +7 -delete

• --single-transaction gives a consistent dump of InnoDB tables without locking them.
• Check the SHOW DATABASES step. If the login fails and you don't check, the loop silently backs up nothing.
• Add set -o pipefail so a failed dump isn't hidden by a successful gzip.

Schedule

Run it only on servers that actually run MySQL:

0 * * * * root /usr/local/bin/backup_mysql.sh >/dev/null 2>&1

Hourly dumps kept for 7 days is 168 copies of each database. Daily, or hourly with fewer days kept, is usually plenty.

Restore

gunzip -c 2026.01.01_03.mydb.sql.gz | mysql mydb