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David
Asked: 2012-01-12 03:21:15 +0800 CST

Nightly Backups and Server Performance

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At a certain time we run a few backup scripts to backup:

  • code/files
  • databases
  • other important files on the server

During this time the websites on the server grind to a hault giving timeouts and database connection issues.

So, i imagine im doing this wrong. What is the bets way to perform nightly backups without affecting the performance of sites on the server?

OS: Centos applications: MySQL, Rsync

Backups are to a remote server.

backup web-server database

2 Answers

  1. Best Answer

    Because of the backup operation there is contention for disk and cpu also maybe network resources, hence your site is not responsive. To avoid this you will have to reduce the io and cpu priorities of the backup operations so that your site can function normally.

    You can use this before you invoke your backup script.

    root@x:~# bash
root@x:~# echo $BASHPID
6576

    BASHID variable is PID of current bash session

    root@x:~# ionice -c 2 -n 7 -p $BASHPID

    This will reduce your current shell's disk io priority

    -c = class ( 0 none, 1 real time, 2 best-effort, 3 idle)

    -n = priority (0-7 , 0 is highest priority)

    root@x:~# renice  +10 -p  $BASHPID

    This will reduce your current shell's cpu scheduling priority (-19 is max priority and 20 is least priority)

    root@x:~# ./backup-script

    Now from here you can invoke your backup script. Since the child processes inherit cpu and io priorities from parent, your backup script process(es) will run with lower io,cpu priorities and therefore your server processes have precedence over backup.

    In case you are using a cron job you can put all above commands in a file , chmod for x permissions and add that file to cron.

    In case network is bottleneck , you may have to use "tc" to classify backup traffic and rate limit it. You can read about rate-limiting here. http://wiki.openvz.org/Traffic_shaping_with_tc

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  2. Difficult to answer without knowing what OS, applications, filesystems, and backup media are involved.

    Without any of that available, my answer is: rsync

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