# \--safe-slave-backup on Master?

**URL:** <https://forums.percona.com/t/safe-slave-backup-on-master/2179>\
**Category:** Percona XtraBackup\
**Created:** [October 24, 2011, 1:22pm UTC](https://forums.percona.com/t/safe-slave-backup-on-master/2179 "2011-10-24T13:22:55Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![dchicks](https://avatars.discourse-cdn.com/v4/letter/d/ed8c4c/32.png) [@dchicks](https://forums.percona.com/u/dchicks)\
**Post date:** [October 24, 2011, 1:22pm UTC](https://forums.percona.com/t/safe-slave-backup-on-master/2179/1 "2011-10-24T13:22:55Z")

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In my preparations to implement a backup strategy with innobackupex, I came across a line in the online documentation that states it is recommended to use the --safe-slave-backup option when backing up master databases. I wanted to ask about it to see if anyone can tell me why this would be recommended?

I’m estimating that my backup against my master database will require somewhere between 90 and 120 minutes. During that time period, a great deal of activity will still be taking place, and it is replicated on 4 other servers. If I halt the slave process during the backup, then my slaves will all be nearly 2 hours behind by the time the backup is finished. Two of the 4 servers are used as read-only replicants. So, the data queried from them would be incorrect for some queries. For this reason, I’m hesitant to use that option when backing up my Master. I’m not even sure I like the idea when backing up my slaves - for the same reason.

Thanks,  
Dave

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**Author:** ![xaprb](https://avatars.discourse-cdn.com/v4/letter/x/49beb7/32.png) [@xaprb](https://forums.percona.com/u/xaprb)\
**Post date:** [October 31, 2011, 7:54am UTC](https://forums.percona.com/t/safe-slave-backup-on-master/2179/2 "2011-10-31T07:54:24Z")

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Can you point to the URL that says this? It’s wrong. This is only needed on a replica. The documentation explains this option:  
[http://www.percona.com/doc/percona-xtrabackup/innobackupex/i](http://www.percona.com/doc/percona-xtrabackup/innobackupex/i) nnobackupex\_option\_reference.html#cmdoption-innobackupex–sa fe-slave-backup

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**Author:** ![dchicks](https://avatars.discourse-cdn.com/v4/letter/d/ed8c4c/32.png) [@dchicks](https://forums.percona.com/u/dchicks)\
**Post date:** [October 31, 2011, 11:11am UTC](https://forums.percona.com/t/safe-slave-backup-on-master/2179/3 "2011-10-31T11:11:05Z")

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Hi Baron,

I could have sworn that it was on this page:  
[http://www.percona.com/doc/percona-xtrabackup/innobackupex/r](http://www.percona.com/doc/percona-xtrabackup/innobackupex/r) eplication\_ibk.html

Either I misread it, or it has already been corrected. I thought I read the last line as:  
“Using this option is always recommended when taking backups from a master server.”