… test as our concern is general IO performance in this case – it is not something MySQL related. I tested things on RHEL5… so many users ? The reality is – for many applications write speed is not so critical so they can sustain this performance… – for example I’m very curios how good is read speed from snapshot (in particular sequential file reads). If you’ve…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
… thread declared inside InnoDB 442 mysql tables in use 1, locked 0 MySQL thread id 8079, query … these variables is indication of IO bound workload. Note however – IO requests submited by threads executing …hash index Innodb builds for some pages to speed up row lookup replacing btree search with hash…
Post: Just do the math!
July 6, 2009 By 4 Comments
… predict it without running benchmarks. There are couple of ways MySQL may execute query above but lest focus on the most… on disk which affects scan speed. Another aspect is the temporary table – the number of rows MySQL can insert/update depends on… slowed down 100-1000 then going from CPU bound to IO bound workload. You can get approximate numbers for other parts…
Post: Estimating Undo Space needed for LVM Snapshot
June 9, 2008 By 5 Comments
… seek, unless they are buffered already. This means your backup speed can be slower than you would expect especially in case… modifications. Now back to our question of space requirements for MySQL Backups using LVM. As you can see from the description… get a lot of junk IO activity causing overhead and eating LVM undo space. For example MySQL on disk temporary files and…
Post: Content delivery system design mistakes
February 11, 2007 By 9 Comments
…helped dealing with performance problems (part MySQL related and part related to LAMP in general)…especially worth to note updating access time needs io even in case content is in OS cache… bit of difference especially on slower connection speeds. Forgetting to set expire Static content rarely changes…
Post: To UUID or not to UUID ?
March 13, 2007 By 28 Comments
… locations in index tree which will require a lot of IO in case of index tree not fitting into memory. This… the point of benchmarks was rather lookup by primary key speed. Lookup speed can be similar or can vary a lot. If… giving load speed of 40305 rows/sec. For UUID process took over 12 hours and is still going. From MySQL status I…
Post: Cache Performance Comparison
August 9, 2006 By 74 Comments
…Associative array. This is to show kind of peak speed possible at all. Furthermore this type of caching …not fit in cache well – you will get disk IO which is very compared to performance of all … but if Unix Socket is used to connect to MySQL MySQL Query Cache will be faster. The explanation for this…
Comment: Disaster: LVM Performance in Snapshot Mode
February 9, 2009 By 55 Comments
…” opens its target with O_DIRECT and does random io with multiple threads. Write percentage controls the ratio… took nearly 15 minutes to come to the raw speeds. Why is that? Look at the write latencies -… good representation of what MySQL is doing so we are currently testing xfs with MySQL. But if my…
Post: XtraDB/InnoDB CPU bound benchmarks on 24cores server
December 29, 2008 By 6 Comments
… bits physical, 48 bits virtual power management: I tested MySQL-5.1.30 with InnoDB plugin, Xtradb-1…thread_concurrency=0 innodb_io_capacity=1000 innodb_write_io_threads = 16 innodb_read_io_threads = 16 join_buffer…the result is dropping down with the same speed as it grew, and with 128 connections we…
Post: How to estimate time it takes Innodb to Recover ?
May 9, 2007 By 7 Comments
… recovery speed during recovery time – the larger buffer pool you have the more pages it can hold and so less IOs will… because to populate buffer pool still a lot of random IO will be required. Number of dirty buffers during the crash… the disk and undo phase – rolling back uncommitted transactions. As MySQL 5.0 these seems to be done in the background…
