…is no comparable variables of how many user variables are allocated (and…. row *************************** SESSION_ID: 7234 TABLE_SCHEMA: test TABLE_NAME: my ENGINE: InnoDB NAME:…509995888 + 2623331) File system 294352 (82672 + 211680) Lock system 318875832 (318747272 + 128560) Recovery system 0 (0 + …
Post: ext4 vs xfs on SSD
March 15, 2012 By 23 Comments
As ext4 is a standard de facto filesystem for many modern Linux system, I am getting a lot of question if this… –test=fileio –file-total-size=${size}G –file-test-mode=rndwr –max-time=3600 –max-requests=0 –num-threads=$numthreads –rand-init=on –file-num=1 –file-extra-flags=direct –file-fsync…
Post: MySQL File System Fragmentation Benchmarks
March 21, 2008 By 28 Comments
Few days ago I wrote about testing writing to many files and seeing how this affects sequential read performance. I was … times. This could be because ext3 does not like so many files in directory or because random updates to 10000 distinct pages… is close, the difference is perhaps explained by the fact files needed to be constantly extended (meta data updates) and reopened…
Post: How innodb_open_files affects performance
November 18, 2009 By 4 Comments
… similar variable – innodb_open_files which defines how many files Innodb will keep open while working in innodb_file_per_table mode. Unlike MyISAM… local file system – one can open/close file hundreds of thousands times per second. To verify this I tried doing “open table” test for…
Post: Working with many files and file system fragmentation
March 18, 2008 By 11 Comments
… a test – creating 100 files writing 4K in the random file for some time and when checking the read speed on the files we… read single file at 80MB/sec while fragmented files only deliver about 2MB/sec – this is a massive difference. The test was done on EXT3 and it looks like it does not do very good job preventing file fragmentation for…
Post: Evaluating IO subsystem performance for MySQL Needs
March 5, 2008 By 23 Comments
…cached mode you can get better performance by having many outstanding requests. Running with more than one threads you…system evaluation benchmark Removing test files… [root@DB10 sysbench]# ./sysbench –test=fileio –max-time=60 –max-requests=1000000 –file-num=128 –file-extra-flags=direct –file…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
…,2) Foreign key constraint fails for table `test/child`: , CONSTRAINT `child_ibfk_1` FOREIGN KEY (`…shows how many inserts were done in insert buffer, how many recs were merged and how many merges … amount of bytes Innodb has written in log files since system tablespace creation. You can also see …
Post: Disaster: LVM Performance in Snapshot Mode
February 5, 2009 By 55 Comments
… there are about twice as many writes as reads. SMALL FILE RUN When I decided to…test=fileio –num-threads=1 –init-rng=on –max-time=60 –file-num=1 –file-total-size=64M –file-extra-flags=direct –file-test… some time and I would expect any system doing writes to experience the “performance shock” …
Post: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 11 Comments
… case offset is correct, but file system is unaware how to align files properly. 4. Partition table and file system properly aligned; sunit/swidth set… were all scripted and oltp benchmarks would automatically start after file tests so if there was an error in the setting, it… setting might be a [mirrored] RAID0 with many more stripes as not having proper file system alignment should have really interesting effects. Large…
Post: Getting MySQL Core file on Linux
August 26, 2011 By 1 Comment
… my system (Ubuntu). You might be lucky and it might work in your system. I also enable multiple “versions” of core files here… to test it for example on the test box, which has same operating system. This is important. There have been many changes to core file handling on Linux and what worked on one system might…
