… far from sequential disk access performance. First you should consider what has to happen with hard drive to read/write the data… issue of disk contention people constantly forgot about. If you ask most people what would be faster for random reads (writes are obvious) – RAID0 or RAID1 most will think they are about the same – in both cases you have 2 disks to…
Post: InnoDB Flushing: a lot of memory and slow disk
March 31, 2011 By 57 Comments
…), your database fits into memory, and your write rate is significant, then the slow disk is, by definition, not able to… changes in memory at a faster rate than it can write to disks. Eventually it gets into an “async” state, where InnoDB… flushing neighbor pages was implemented to perform sequential writes where possible and avoid random writes, which is quite critical for hard drives…
Comment: Heikki Tuuri to answer your in depth Innodb questions
September 28, 2007 By 51 Comments
… memory. This way every write is serial so that we can see the full write speed of the disk for throughput. INNODB uses fuzzy checkpointing to commit data to disk. The problem that…% of the raw disk write speed. Since the commit isn’t perfectly serial it’s having to seek on disk which slows down…
Post: Jeremy Cole on MySQL Replication
May 27, 2006 By 12 Comments
… sequential writes this is why sync_binlog changes things. Two logs are synced now which requires seeks which make certain disks to… same track we’ll be only able to do single disk write per rotation, which is about 250 for 15000 RPM drive… really affected by this if you have a lot of writes to large database size. This is one more reason why…
Post: Innodb Double Write
August 4, 2006 By 24 Comments
… called “doublewrite” It means Innodb will write data twice when it performs table space writes – writes to log files are done only once… battery backed up cache. If there is single write issued to the disk itself it should be in theory completed even if… will be written to double write buffer (sequentially), fsync() called to ensure they make it to the disk, then pages written to…
Post: MLC SSD card lifetime and write amplification
November 15, 2011 By 8 Comments
… the 1h interval, and it will show write how many bytes per hour we write, and in such way to calculate the… it is vgc-monitor -d /dev/vgca | grep writes 379835046150144 (379.84TB) (writes) Having this info let’s take look what a… 1,500 deletes/sec, which corresponds to write throughput 273.45MB/sec from MySQL to disk. And it helps to calculate the…
Comment: Finding your MySQL High-Availability solution – The questions
January 8, 2010 By 36 Comments
…). There are a lot of disk writes with LCPs and redo logs but typically LCPs are quite slow writes (default 10MB/sec). With… put to disk quickly, so fast disks are important for this aspect, especially on a database with a lot of writes. I would rather a lot of disk…
Post: InnoDB, InnoDB-plugin vs XtraDB on fast storage
January 13, 2010 By 13 Comments
… and taking fact that FusionIO is not perfect for sequential writes http://www.mysqlperformanceblog.com/2010/01/11/fusionio-320gb-mlc… CPU usage and disk utilization. Disk throughput: CPU (user) usage: Even with improvements, XtraDB performs less 150MB/s in disk writes (from benchmarks we… the same but with all files on RAID10 with regular disks, the graph is there: with final result: 2873.783 NOTPM…
Post: Tokyo Tyrant -The Extras Part III : Write Bottleneck
November 12, 2009 By 3 Comments
… Can have only a single writer thread, bottlenecking performance When writing an application using Tokyo Cabinet only one connection can be… multiple applications but it still single threads them when writing out to disk.  If you run several threads all just…, and your writes will start to peter out quickly. In my tests when I was not disk bound (FS Cache writes) I was…
Post: Linux schedulers in tpcc like benchmark
January 30, 2009 By 19 Comments
… Here is graph of disk writes (column bo in vmstat) during benchmark As you see noop / deadline can utilize disks much better. For….net/perconatools, generated 100W (about 9.5GB of data on disk), and used next XtraDB params: [mysqld] #mysqld options in alphabetical… innodb_thread_concurrency=0 innodb_flush_method = O_DIRECT innodb_write_io_threads=4 innodb_read_io_threads=4 innodb_io…
