…’t like DRBD with virtual machines. First is the disk IO performance hit that comes with DRBD. When you run a… other reason is because virtual machines tend to handle process scheduling and timing much differently than traditional hardware, and I’ve…
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…
Post: XtraDB benchmarks - 1.5X gain in IO-bound load
December 18, 2008 By 30 Comments
… to run MySQL on. What is important I used Noop IO scheduler, instead of default CFQ. Disclaimer: Please note you may not… 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… inside of database system itself. Normal – As name implies normal IO should be done with this priority – such as reading data… want to happen in background when there are enough resources. IO Scheduler should execute these only if there is bandwidth available so…
Post: Linux schedulers in tpcc like benchmark
January 30, 2009 By 19 Comments
I mentioned earlier that IO scheduler CFQ coming by default in RedHat / CentOS 5.x may … reported that just changing cfq to noop solved their InnoDB IO problems. I ran tpcc scripts against XtraDB on our Dell…_flush_method = O_DIRECT innodb_write_io_threads=4 innodb_read_io_threads=4 innodb_io_capacity=800 innodb_adaptive_checkpoint=1 max…
Post: Performance impact of complex queries
January 17, 2007 By 11 Comments
… more than few milliseconds you would expect disk IO to take. Scheduling Issues OS Disk IO schedules may also “help” in this case. Number… movement, compared to IO requests in random locations other threads are willing to take. Especially some older disk schedulers could be poor… couple of files. In recent Linux Kernels deadline or cfq IO schedulers should be better with this. So what can you do…
Post: Setting up XFS on Hardware RAID -- the simple edition
December 16, 2011 By 9 Comments
… 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…. Two steps here: echo noop > /sys/block/sda/queue/scheduler # update the scheduler in realtime And to make it permanent, add ‘elevator…
Post: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 13 Comments
….8 ns) DIMM {OUT OF SPEC} Other … # Disk Schedulers And Queue Size ############################# sda | [deadline] 128 # RAID Controller ############################################ …the goal was to compare performance with different IO alignment, not different MySQL configurations, I didn’…
Comment: Evaluating IO subsystem performance for MySQL Needs
March 5, 2008 By 23 Comments
The IO scheduler matters for this test as well, even when using O_DIRECT-deadline should win. What is your IO scheduler setting? Most… for this test, when RAID-10 is perfect for random IO? For testing disks set-up to get theoretical throughput, have…
Comment: XtraDB benchmarks - 1.5X gain in IO-bound load
December 18, 2008 By 30 Comments
Matt, Indeed schedulers are workload specific and hardware specific and workload specific and … we had to change a scheduler from default to get very significant performance increase. The problem with Schedulers on OS level is… with large number of hard drives, or SSD the assumptions IO schedulers operate are just wrong. NOOP reduces extra kernel load and…
