…sure to stripe the LV when we need to and align the partition correctly. We got decent tpcc performance,… The tpcc database, which contains a lot of random data that doesn’t compress well showed a…other drive in the mirror. Better availability and disk usage On purpose, I allocated mirror pairs using…
Post: How multiple disks can benefit for single client workload ?
April 26, 2008 By 4 Comments
…outstanding requests to the disk. Though this does not help dramatically for many “random” update queries. After …single disk. Assuming it is not fragmented it will take N tracks on this disk. Now if we stripe…can use any disk to perform the read request while with RAID0 it is only the disk which has…
Post: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 13 Comments
… WT cache enabled, single thread performance improvement is marginal however WB cache brings single thread random write performance close to what 8 threads… most relevant to databases – random reads and random writes – IO alignment on a 4-disk RAID10 with standard 64k stripe element size makes a…
Comment: Aligning IO on a hard disk RAID – the Theory
June 9, 2011 By 18 Comments
… Stripe Size: The stripe size specifies the size of the segment written to each disk in a RAID configuration. You can set the stripe… 128 Kbytes. A larger stripe size produces higher read performance. If your computer regularly performs random read requests, choose a smaller stripe size. The default…
Post: Impact of logging on MySQL’s performance
February 10, 2009 By 8 Comments
… immediately a question arises how much logging impacts on performance. When we do performance audit often we log every query to find….66GHz, 32GB RAM. There are 8 disks in RAID10(a mirror of 4+4 striped disks). Software It was used MySQL 5.0… run 5 times and random measurement error was calculated. As it is seen from the chart above the performance almost doesn’t…
Post: Intel 320 SSD read performance
July 29, 2011 By 11 Comments
… I wrote about write performance of these cards, and now let’s take look on a random read workload. … it: regular RAID10 over 8 SAS 2.5 disks single Intel 320 SSD directly attached to a … read performance. A single card provides 5-8x better throughput and 10-14x better response time. Striping helps …
Comment: MySQL 5.5.8 - in search of stability
January 4, 2011 By 11 Comments
…I disagree that the doublewrite buffer won’t limit performance. I can produce results showing that it does…use background IO threads to do random writes in place 5) fsync the random writes Note that step #5… use a small number of disks given a reasonable RAID stripe. The other disks won’t be doing any…
Comment: Evaluating IO subsystem performance for MySQL Needs
March 29, 2008 By 23 Comments
… a RAID unit (whether controller or disk stack), the cfq elevator comes with a ~20% performance penalty. Why? Because unless you’re exposing the spindles to the OS one-by-one (or in RAID-1 pairs striped with MD/LVM), you’re having cfq order all the random reads/writes to the disk within one I…
