Search Results for: linux

Getting MySQL Core file on Linux

Core file can be quite helpful to troubleshoot MySQL Crashes yet it is not always easy to get, especially with recent Linux distributions which have security features to prevent core files to be dumped by setuid processes (and MySQL Server is most commonly ran changing user from “root” to “mysql”). Before you embark on enabling […]

Linux failing to boot screen on the plane

I’ve seen Windows Blue Screen of Death, stalled boot process or simply application error dialog on many big information screens in shops, airports and other places as well in other systems such as cache machines, airport self checking systems or photo print kiosk. Today coming back from US on NorthWest Airbus A330 we got stalled […]

Linux IO Schedulers and MySQL

Found a great article about Linux IO Schedulers today which is quite interesting. It goes in details about schedulers and explains in which of workloads which of schedulers is best. The interesting thing this article points out is – there are multiple versions of each of the schedulers, while name remains the same. This means […]

Looking deeper into InnoDB’s problem with many row versions

A few days ago I wrote about MySQL performance implications of InnoDB isolation modes and I touched briefly upon the bizarre performance regression I found with InnoDB handling a large amount of versions for a single row. Today I wanted to look a bit deeper into the problem, which I also filed as a bug. First […]

Hyper-threading – how does it double CPU throughput?

The other day a customer asked me to do capacity planning for their web server farm. I was looking at the CPU graph for one of the web servers that had Hyper-threading switched ON and thought to myself: “This must be quite a misleading graph – it shows 30% CPU usage. It can’t really be […]

Testing backup locks during Xtrabackup SST on Percona XtraDB Cluster

Background on Backup Locks I was very excited to see Backup locks support in release notes for the latest Percona XtraDB Cluster 5.6.21 release. For those who are not aware, backup locks offer an alternative to FLUSH TABLES WITH READ LOCK (FTWRL) in Xtrabackup. While Xtrabackup can hot-copy Innodb, everything else in MySQL must be locked (usually […]

MySQL 5.6 Transportable Tablespaces best practices

In MySQL 5.6 Oracle introduced a Transportable Tablespace feature (copying tablespaces to another server) and Percona Server adopted it for partial backups which means you can now take individual database or table backups and your destination server can be a vanilla MySQL server. Moreover, since Percona Server 5.6, innodb_import_table_from_xtrabackup is obsolete as Percona Server also […]