…DRBD with virtual machines. First is the disk IO performance hit that comes with DRBD. When you…The other reason is because virtual machines tend to handle process scheduling and timing much differently than traditional … to keep an eye on to prevent a problem before it occurs. For example, if you see…
Post: Scaling problems still exist in MySQL 5.5 and Percona Server 5.5
May 20, 2011 By 11 Comments
… and Percona Server 5.5 do not solve all scalability problems even for read only workloads. Workloads which got a lot… is almost perfect scalability. So there are workloads where the problem is solved and when there are where a lot of… 10 libaio::??,os_aio_linux_collect,os_aio_linux_handle,fil_aio_wait,io_handler_thread,start_thread,clone 5 pthread_cond…
Comment: Sysbench evaluation of iSCSI performance
April 12, 2012 By 2 Comments
… the storage of innodb, we may encounter the problem：the failure of the IO operation. Innodb access the data from the remote…, so the IO of INNODB may be wrong. In my view, innodb(mysql5.5) can not slove the wrong io problem and it will be coredump like that. eg: in “fil_aio_wait”, if “os_aio_linux_handle” return false…
Page: Tools
May 30, 2008 By 31 Comments
… tool is a great help investigating/troubleshooting IO problems – it will show you amount of IOs happening per device, their type, request size… are different CPUs are being used, how many interrupts the handle etc. Helps to better understand and fine tune the load…. iohist iohist is a little tool to show histogram for IO response time. The main use for it is to see…
Post: MySQL Users Conference - Innodb
May 9, 2007 By 6 Comments
… should benchmark this aspect separately. Improved Auto Increment handling Yet another known Innodb problem is table locks which are taken for statement… when statement is started instead of handling auto increment lock for full statement duration. The problem with multi value inserts however is… however needs to test properly before really enabling it. Innodb IO Tuning I should also mention Paul Tuckfield Keynote about Scaling…
Post: Why do you need many apache children ?
February 5, 2007 By 15 Comments
… scheduling and switching overhead to become serious problem. Depending on application and hardware this “optimal”…-fork mode) to get decent performance ? Network IO – This is actually the only valid one…. caching or lower timeout is other story 
Handling Keep Alive – Keep alive connection in Apache…
Post: Using LoadAvg for Performance Optimization
December 4, 2006 By 5 Comments
…”uninterruptable sleep” state which typically corresponds to disk IO. You can also map LoadAvg to VMSTAT output … Average does not mean there are no performance problems, for example if you run single batch …point – how much more load the box can handle before it overloads, loadavg skyrockets and it …
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
… like another magic number to experiment with. Q17: How InnoBD handles blobs/text fields (needs more info) According to the documentation… checkpointing to commit data to disk. The problem that we’ve seen in high IO scenearios is that it commits too often… or 2 often solves your thrashing problem. PZ: Values 1,2 may solve your thrashing problem but also will limit innodb to…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
…probably heard complains about MySQL being unable to handle more than 1.000.000 (or select …combine index access with data access, saving you IO for completely disk bound workloads. There are …index lookups which could be random accesses. This problem exists for all kinds of applications, however for…
Post: State of MySQL Market and will Replication live ?
April 9, 2008 By 29 Comments
…were clearly not enough to solve all performance problems (like scaling Writes with replication or dealing … to get very fast IO and so consolidate system suffering from IO bound workloads. There is… with concepts which are not very efficiently handled with SQL and relational operations (think social …
