… is xfs, and it comes to known problem in ext3, where IO gets serialized per i_node in O_… I was asked, namely: “If MySQL 5.5 uses async IO, is innodb_write_io_threads still important?”, and it …}G prepare sync echo 3 > /proc/sys/vm/drop_caches for numthreads in 4 do sysbench –test=fileio –file-…
Comment: Disaster: LVM Performance in Snapshot Mode
February 9, 2009 By 55 Comments
… in the cache. So what should be a very fast write under normal circumstances (write-back cache) turns into a read and a write while… cached and ext3 resumes the “raw” performance. But once the snapshot is created it plummets again. It’s the same reason – a write… write ratio has even a more drastic effect on ext3 + snapshot performance. “randomio” might not be a good representation of what MySQL is…
Post: MySQL File System Fragmentation Benchmarks
March 21, 2008 By 28 Comments
… tests for MyISAM and Innodb tables on ext3 filesystem. Here is what I found: The …10000000; mysql -e’drop database test1′; mysql -e’create database test1′; done; tables: 1; total records: 10000000; write … random tables. I used default MySQL settings for MyISAM (table_cache=64) and set innodb_buffer_…
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
…-query-demo-data-flatfiles 30GB ext3 EBS This is an ext3 volume which contains the flat…0 innodb-use-sys-stats-table innodb-write-io-threads=4 join-buffer-size=16M…cache=16384 table-open-cache=128 thread-cache-size=32 thread-stack=256K tmp-table-size=64M transaction-isolation=READ-COMMITTED user=mysql…
Post: table_cache negative scalability
November 16, 2009 By 23 Comments
… Xeon E5405, 16GB RAM and EXT3 file system on the SATA hard drive. MySQL 5.0.85 Created 100….which is a great speed. We can note significant writes to the disk during this read-only benchmark. Why ?…MySQL 5.1, lets see how MySQL 5.4 behaves. MySQL 5.4.2 MySQL 5.4.2 has higher default table_open_cache…
Comment: SSD, XFS, LVM, fsync, write cache, barrier and lost transactions
March 9, 2009 By 32 Comments
… need to disable write cache. (Basically reducing random write IOPS from 5000+ to 1200ish.) Is this issue XFS specific or MySQL specific or is it hardware? Does it happen in EXT3… are forced to disable the write cache on it and accept 1200 random write IOPS compared to 5K+ random write IOPS. I can foresee…
Comment: Linux schedulers in tpcc like benchmark
January 31, 2009 By 19 Comments
… size is reached). Domas, does this differs from ext3‘s data=writeback side effects? Peter, my comment … schedulers do reorder based on kernel’s page cache content (so, it seems I was wrong), and … it, MySQL using O_DIRECT to move data from sequentially written log files to the more write-costly …
Post: Slow DROP TABLE
June 16, 2009 By 21 Comments
… – write lock …cache * from other_table limit 1 | +—–+——+———–+——+———+——+—————-+————————————————+ I tried some alternative approaches to trick MySQL…EXT3 mysql> drop table large_table; Query OK, 0 rows affected (7.44 sec) XFS mysql…
Post: Innodb Performance Optimization Basics
November 1, 2007 By 70 Comments
… for database directory to get more efficient backup. EXT3 file system works OK in most cases, though … OS so it would not swap out MySQL out of memory. MySQL Innodb Settings The most important ones are…you do not have battery backed up RAID cache as when write IO may suffer. innodb_file_per_table – …
Comment: Slow DROP TABLE
June 17, 2009 By 21 Comments
…using a disk store like ext3: 1) Our database is typically 100% cached (both data and indexes), 16 …not an issues since all reads are cached and the few writes we have are not performance critical…dedicated to caching the db / indexes). I’d go spelunking, but have no experience with the mysql codebase…
