On Sun, Oct 12, 2014 at 5:56 AM, Stefan Mayr <ste...@mayr-stefan.de> wrote:
> 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 > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > > Stefan, Thanks, that seems to be the problem. We have all InnoDB, and the backup runs without locks, but the it runs under fairly heavy IO load. It seems like turning 'innodb-stats-on-metadata' to OFF lessened the strain that the SHOW STATUS queries from XtraBackup caused. Bumping up maxActive allowed the pool to handle the slowdown of application queries during the backup. This has worked so far but if it repeats I'll look into the throttling. That was my first sense, that it wasn't locking, just pushing too hard on the DB. Very helpful. Thanks. -John
