… asked how one can evaluate IO subsystem (Hard drive RAID or SAN) performance for MySQL needs so I’ve decided to write… by RAID cache and uncached IO performance. We’re interested in cached reads because they may show latency to the RAID cache if RAID… 0 73 26 You can get similar information by analyzing iostat numbers and that well may be more accurate. Though looking…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…concerns are at this stage. Is it the current performance, future performance, scalability, ability to recover from disasters? We … of information on the box’s hardware, including RAID controllers, installed memory, and so on in the … to use in some cases): vmstat 5 5 iostat -dx 5 5 If you don’t know …
Post: Innodb Fuzzy checkpointing woes
May 10, 2006 By Leave a Comment
… hosting and powerful RAID system may have very different performance properties. This means for example if you have RAID system which does 5000 IOs/sec and you have relatively idle interval of performing just 500 IOs… itsef.  Should we get utilization ratios from OS (ie iostat) – this is nice but needs to be done for all…
Post: MySQL 6.0 vs 5.1 in TPC-H queries
March 25, 2008 By 17 Comments
…big improvements with using MRR here. What is interesting is iostat -dx 5 output during query execution. For 5.1 I… As you see 1285 rkB/s is pretty small for RAID 10 system we have on this server. This is …KEY (li_shp_dt_idx) (full table scan will be performed in this case) then we got: 1 min 39.14…
Comment: Predicting Performance improvements from memory increase
August 21, 2008 By 6 Comments
…. If you have single drive 100% utilization as reported by iostat actually means drive is 100% busy because there is at… driving performance higher than it was when it was 100% busy with only one request. When you get to the RAID it… pegged. In practical terms I look at “wa” in VMSTAT, iostat -dx utilization rate as well as service time and average…
Post: Learning about MySQL Table Fragmentation
May 1, 2008 By 20 Comments
…worth to notice you can see poor sequential scan performance even if table is not logically fragmented and …. If you see small IO request sizes in iostat and simply read speed. Like for the customer … much better than 10MB/sec but well below RAID array capacity. To check if file fragmentation is …
