… values since the server was booted; the second and subsequent are incremental differences. I’ll…Aborted_clients | 205174 | 6 | | Aborted_connects | 29 | 0 | | Binlog_cache_disk_use | 0 | 0 | | Binlog_cache_use | 9630066 | 468 |… it’s a cheap query. It adds hardly any load. But for the application, it…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
… random lookups per second from single thread depending on system and table structure. Now if you data fully on disk (both data… per second for fully sequential access, jam packed rows – quite possible scenario for MyISAM tables. Now if we take the same hard… means if single query execution time is your concern many hard drives and large number of CPUs will not help. Sometimes…
Post: Estimating Undo Space needed for LVM Snapshot
June 9, 2008 By 5 Comments
…need to be read from undo space will require disk seek, unless they are buffered already. This means …of backup you will need 10GB of undo space. Second, limit batch activities – Backups are often done at … for large database with little no – connect USB hard drive place LVM snapshot on it and you …
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
… with multiple IO threads on systems with large amount of hard drives. Google has Patches which let you to try it…=2, that is, to flush the log to the disk only once per second. PZ: We’ve helped number of users who… Heikki, Remember we’re waiting you to answer second portion of the questions. UPDATE: Second Part of the answers is now available
Post: Modeling MySQL Capacity by Measuring Resource Consumptions
March 8, 2011 By 1 Comment
… which requires 1 CPU second and 1 IO to execute and we have 16 core system with hard drive which can do 100 IOPS we will be consuming all CPU when we’re running 16 seconds per second. Of…_reads , Innodb_data_writes, Innodb_os_log_fsyncs for your disk IO estimation. When you can divide it per number of…
Post: Recovering Linux software RAID, RAID5 Array
August 27, 2011 By 2 Comments
… failed hard drive will be completely inaccessible, this happens even you just happen to be one bad sector on the disk. This… (‘A’ == active, ‘.’ == missing) Note the Update time here. The oldest disk to fail will have earliest update time. Here is the… a file or two. The second way is to get something like Drive Fitness Test (different hard drive vendors have different versions…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
… OUTPUT ===================================== Per second averages calculated from the last 44 seconds Make sure data is sampled for at least 20-30 seconds. If averages… 1 second they are pretty much unusable. To be honest I do not really like averages Innodb provides as it is hard… writes Innodb has to ensure data makes it to the disk – just passing it to OS cache is not enough. This…
Post: When is it a time to upgrade memory ?
September 16, 2008 By 11 Comments
… at number of misses per second Check number of innodb file reads and writes per second and see how high are these… the load. If you just get couple of reads per second your working set fits to the memory very well if… there are rarely anyone waiting from disk to service requests. Look at Trends Really it is hard to give advice without trending…
Post: Side load may massively impact your MySQL Performance
November 13, 2011 By 7 Comments
…have relatively little CPU needs and be bound by disk. Also these are just 2 “threads” running on …and mysqldump for large table completes in about 95 seconds. If we run them concurrently after system reaches …now have 2 threads competing for what is single hard drive on this test system. It is worth …
Post: Virtualization and IO Modes = Extra Complexity
March 21, 2011 By 12 Comments
… lot of troubles with fsync() not flushing hard drive write cache and so potential hard drives can be lost on power failure… over 100 writes per second as even in case there is no disk seek we need to wait for disk head to make… times only writes not fsync() calls…. 22 fsync requests per second is pretty bad though I assume It can be realistic…
