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Date: Sun, 12 Oct 2014 11:56:28 +0200
From: Stefan Mayr <stefan@mayr-stefan.de>
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Subject: Re: Tomcat Connection Pool Problems with XtraBackup
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Hi John,

Am 11.10.2014 23:30, schrieb John Smith:
> I'm trying to workout a managed backup scheme on a MySQL production
> database with XtraBackup. According to our DBA, XtraBackup doesn't lock the
> database, but issues a series of SHOW TABLE STATUS commands and then works
> on the file system level.
>
> Still, just as XtraBackup runs my logs start to blow up with connection
> pool errors:
>
> Error getting database connection:[http-nio-8080-exec-5] Timeout: Pool
> empty. Unable to fetch a connection in 10 seconds, none available[size:100;
> busy:100; idle:0; lastwait:10000].
>
> There's some suggestion that turning off 'innodb-stats-on-metadata' might
> help so we're trying that.
>
> ...
> Anything else seem like it could be tweaked in relation to XtraBackup?
>
> TIA,
> John
>

XtraBackup can operate without locks if your database contains only 
InnoDB tables. For other storage engines like MyISAM it still uses 
locks. A problem we seen is high IO load during XtraBackup. Your DBA 
could check iostats while backup is in progress. If this makes your 
database server unresponsive he could try to throttle the backup: 
http://www.percona.com/doc/percona-xtrabackup/2.2/innobackupex/throttling_ibk.html

-Stefan

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