April 17, 2014

Intel 320 SSD read performance

(this is cross-post from http://www.ssdperformanceblog.com/) While PCI-e Flash cards show great performance, I am often asked about alternatives, as price for PCI-e cards is still significant and not acceptable for small companies and startups. Intel 320 SSD appears to be a popular drive with a quite acceptable price. I wrote about write performance of these […]

Multiple purge threads in Percona Server 5.1.56 and MySQL 5.6.2

Part of the InnoDB duties, being an MVCC-implementing storage engine, is to get rid of–purge–the old versions of the records as they become obsolete.  In MySQL 5.1 this is done by the master InnoDB thread.  Since then, InnoDB has been moving towards the parallelized purge: in MySQL 5.5 there is an option to have a […]

MySQL Limitations Part 1: Single-Threaded Replication

I recently mentioned a few of the big “non-starter” limitations Postgres has overcome for specific use cases. I decided to write a series of blog posts on MySQL’s unsolved severe limitations. I mean limitations that really hobble it for major, important needs — not in areas where it isn’t used, but in areas where it […]

SSD: Free space and write performance

( cross posting from SSD Performance Blog ) In previous post On Benchmarks on SSD, commenter touched another interesting point. Available free space affects write performance on SSD card significantly. The reason is still garbage collector, which operates more efficiently the more free space you have. Again, to read mode on garbage collector and write […]

Analyzing the distribution of InnoDB log file writes

I recently did a quick analysis of the distribution of writes to InnoDB’s log files. On a high-traffic commodity MySQL server running Percona XtraDB for a gaming workload (mostly inserts to the “moves” table), I used strace to gather statistics about how the log file writes are distributed in terms of write size. InnoDB writes […]

Purge Thread Spiral of Death

I just wrote a large post on reasons for innodb main tablespace excessive growth and I thought it would make sense to explain briefly of why it is so frequently you have purge not being the problem at all and when out of no where you can see purge thread being unable to keep up […]


A week or so ago at the MySQL conference, I visited one of the backup vendors in the Expo Hall. I started to chat with them about their MySQL backup product. One of the representatives told me that their backup product uses FLUSH TABLES WITH READ LOCK, which he admitted takes a global lock on […]

Maximal write througput in MySQL

I recently was asked what maximal amount transactions per second we can get using MySQL and XtraDB / InnoDB storage engine if we have high-end server. Good questions, though not easy to answer, as it depends on: – durability setting ( innodb_flush_log_at_trx_commit = 0 or 1 ) ? – do we use binary logs ( […]

Tokyo Tyrant -The Extras Part III : Write Bottleneck

This is part 3 of my Tyrant extra’s, part 1 focused on durability, part 2 focused on the perceived performance wall. #3.  Tokyo Cabinet Can have only a single writer thread, bottlenecking performance When writing an application using Tokyo Cabinet only one connection can be opened as a “writer”  while the rest are readers.  Tyrant […]

SSD, XFS, LVM, fsync, write cache, barrier and lost transactions

We finally managed to get Intel X25-E SSD drive into our lab. I attached it to our Dell PowerEdge R900. The story making it running is worth separate mentioning – along with Intel X25-E I got HighPoint 2300 controller and CentOS 5.2 just could not start with two RAID controllers (Perc/6i and HighPoint 2300). The […]