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MySQL dump done right


Such a common problem: site had an emergency crash, and needed to restore from backup.

• They discovered the last six months of backups had been sent to a 100% full filesystem – none of the backups were restorable.

• It’s hard for a business to recover from this kind of mistake – you may be turning off the lights


Once your database less than few GiB mysqldump fits well, so let's do it through crontab. To prevent any unexpected issues we do set -e (bash -e) that causes the shell to exit if any subcommand or pipeline returns a non-zero status. Let's assume we use s3cmd CLI to upload file onto AWS S3, you can easily replace it with rsync or something else.

mkdir -p /mnt/backup

echo '#!/bin/bash -e
current_date=`date +%Y-%m-%d-%H:%M`
mysqldump --innodb-optimize-keys --single-transaction -u user db | gzip -c > $dbfile_full
log=$(s3cmd put -sv s3_bucket:mysql/$dbfile_name $dbfile_name 2>&1)
echo $log | mail -s "[backup] DB#0" your_email@domain.com
/bin/sync; echo 1 > /proc/sys/vm/drop_caches;
' > /mnt/backup.sh

echo "0 */24 * * * /mnt/backup.sh" | crontab -

What does exactly this simple script do:

• makes sure that script stop immediately if something goes wrong (-e option)

• once you receive an email the dump files uploaded successfully

• you can track the dump file size and see if db slave still alive

• all emails will be organised in thread by title to easy tracking

• prevents swap by cleaning the file cache straight after dump file is uploaded

• once you stopped from receving emails you know that filesystem is 100% full in most cases

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