… MySQL 5.1 + InnoDB-plugin and later MySQL 5.5 (or equally Percona Server 5.1 and 5.5), InnoDB uses “asynchronous” IO… question I was asked, namely: “If MySQL 5.5 uses async IO, is innodb_write_io_threads still important?”, and it seems it…. I would still use value 2 or 4, to avoid scheduling overhead from single thread, but it does not seem critical…
Post: Linux IO Schedulers and MySQL
January 30, 2007 By 7 Comments
… Linux IO Schedulers today which is quite interesting. It goes in details about schedulers and explains in which of workloads which of schedulers is… was not really significant. This article also points out benchmarking IO schedulers you should look at more numbers than aggregate bandwidth – you… the docs it is mentioned it uses “per process” scheduling while MySQL is single process but single thread – does each thread gets…
Post: XtraDB benchmarks - 1.5X gain in IO-bound load
December 18, 2008 By 30 Comments
… quite typical server we recommend to run MySQL on. What is important I used Noop IO scheduler, instead of default CFQ. Disclaimer: Please… better. Finally let me show you why I took NOOP IO scheduler instead of CFQ, there are result for XtraDB with both….2) are coming with CFQ scheduler as default. So echo ‘noop’ > /sys/block/sda/queue/scheduler should be one of first things…
Post: Operation Systems do not provide good IO interface for Database Servers
May 11, 2006 By 2 Comments
… priority is not accounted for while executing IO request. Last time I checked there was IO scheduler with these functions in works for… want to happen in background when there are enough resources. IO Scheduler should execute these only if there is bandwidth available so… DIKU We tested some protototype patches for Linux kernel and MySQL but we did not get anything ready for production up…
Post: Linux schedulers in tpcc like benchmark
January 30, 2009 By 19 Comments
… mentioned earlier that IO scheduler CFQ coming by default in RedHat / CentOS 5.x may be not so good for MySQL. And yesterday one customer reported that just changing cfq to noop solved their InnoDB IO problems. I ran…_flush_method = O_DIRECT innodb_write_io_threads=4 innodb_read_io_threads=4 innodb_io_capacity=800 innodb_adaptive_checkpoint=1 max…
Post: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 11 Comments
…8 ns) DIMM {OUT OF SPEC} Other … # Disk Schedulers And Queue Size ############################# sda | [deadline] 128 # RAID Controller ############################################… with different IO alignment, not different MySQL configurations, I didn’t try out different MySQL versions or settings…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…am constantly referring to the amazing MySQL manual, especially the option and variable reference table. But just…_threadsblogpercona.commanual innodb_read_ahead_thresholdblogpercona.commanual innodb_read_io_threadsblogpercona.commanual innodb_replication_delayblogpercona.commanual innodb_rollback_on…
Post: MySQL Users Conference - Innodb
May 9, 2007 By 6 Comments
… many MySQL patches so we can call patched version GoogleSQL. Among them there are number of patches to make Innodb IO scheduling more aggressive which is important for serious IO subsystems. Many Innodb IO settings were optimized on systems… they are far from optimal for server grade IO subsystems. These are for MySQL 4.0 at this point but we hope…
Post: Setting up XFS on Hardware RAID -- the simple edition
December 16, 2011 By 9 Comments
…: /var/lib/mysql xfs nobarrier,noatime,nodiratime Setting the IO scheduler This is a commonly missed step related to getting the IO setup properly. The best choices here are between ‘deadline’ and ‘noop’. Deadline is an active scheduler, and noop simply means IO…
Post: Performance impact of complex queries
January 17, 2007 By 11 Comments
… your normal working set from OS cache. Operation Systems and MySQL Itself employs various strategies to attempt to minimize such effect… more than few milliseconds you would expect disk IO to take. Scheduling Issues OS Disk IO schedules may also “help” in this case. Number… couple of files. In recent Linux Kernels deadline or cfq IO schedulers should be better with this. So what can you do…
