Here on the Percona Support team we often ask customers to retrieve disk stats to monitor disk IO and to measure block devices iops and latency. There are a number of tools available to monitor IO on Linux. iostat is one of the popular tools and Percona Toolkit, which is free, contains the pt-diskstats tool for this purpose. The pt-diskstats tool is similar to iostat but it’s more interactive and contains extended information. pt-diskstats reports current disk activity and shows the statistics for the last second (which by …

Join me online next week (September 10 at 10 a.m. PDT) for my live webinar on Migrating to Percona XtraDB Cluster.  This was a popular webinar that I gave a few years ago, so I’m doing it again with updates for Percona XtraDB Cluster 5.6 (PXC) and all the latest in the Galera world.

This webinar will be really good for people interested in getting an overview of what PXC/Galera is, what it would take to adopt it for your application, and some of the differences and challenges it brings compared with a conventional MySQL Master/slave setup.  I’d highly suggest attending if you are considering Galera in your environment …

Download MariaDB Galera Cluster 10.0.13

Release Notes Changelog What is MariaDB Galera Cluster?

MariaDB APT and YUM Repository Configuration Generator

The MariaDB project is pleased to announce the immediate availability of MariaDB Galera Cluster 10.0.13. This is a Stable (GA) release.

See the …

Spil Games hackday At Spil Games we organise a monthly hackday (actually the last two Thursday/Friday of the month) where several teams try to hack something in limited amount of time. The only rules for the hackday are: make something cool, keep it simple, document it, learn something and have fun. In general it means time is […]

The post Spil Games hackday: research MaxScale appeared first on Spil Games Engineering.

September 3, 2014 By Severalnines

Running your database cluster on AWS is a great way to adapt to changing workloads by adding/removing instances, or by scaling up/down each instance. At Severalnines, we talk much more about scale-out than scale up, but there are cases where you might want to scale up an instance instead of scaling out. 

In this post, we’ll show you how to change instance sizes with respect to RAM, CPU and IOPS, and how to tune your Galera nodes accordingly. Moreover, this post assumes that instances are launched using Amazon VPC.

When do we need to upgrade an instance?

You typically need to upgrade an instance when you run out of server resources. This includes CPU, RAM, storage capacity, disk throughput and bandwidth. You must allow enough headroom for …

Schedule Builder allows you to effectively plan your conference and pre-enrol in MySQL Central sessions you want to attend. In addition to the keynotes, you can schedule your attendance to conference sessions delivered by Oracle's MySQL engineers, MySQL customers, community members and partners, as well as plan to attend tutorials, hands-on labs and Birds-of-a-Feather sessions. Plus, you can also plan to join all the Oracle OpenWorld keynotes, extensive content and entertainment!

The MySQL Central "Focus On" document provides you an overview of the MySQL Central content (note that one additional tutorial will shortly be added to the doc so …

We are pleased to announce our attendance at the PyCon New Zealand in Wellington, New Zealand, on September 12-14, 2014! This time we do not have a booth, but will be very actively going around and talk to you. Find our staff wearing MySQL t-shirt!

Anyway if you are interested our colleague from the Solaris Modernization team, James C. McPherson is going to have a talk on Why Python rocks Solaris. Come to hear James' talk scheduled for Saturday, Sep 13 @ 11:20 am (Track 1). 

Let me start by saying a big “thank you” to the staff at Oracle for deciding to open source reducer.sh. It’s a tool I developed whilst I was working for them several years ago. Its sole purpose is to do one thing – but do it good: test-case simplification.

So, let’s say some customer just sent you 120,000 lines of SQL code and affirms that “it definitely causes a crash.” Or maybe you ran RQG (the Random Query Generator) for awhile (with the general query log turned on) and now you have a nice SQL trace which may just lead to that crash the run resulted in. Or you’re a DBA testing the company’s usual queries with Valgrind, and noticed that 2 in 1000 queries give a Valgrind warning in the mysqld error log – you’re just not sure which one. Or maybe you’re a developer, and during testing you saw that a SELECT query output did not look the way it should – the output was “7″ where it should have been “5″ – the …

Given the recent excitement & interest around OpenStack I wanted to make sure I was ready to conduct appropriate evaluations of system performance.  I generally turn to sysbench since it comes with a variety of different tests (accessed via –test= option interface), including:

• fileio – File I/O test
• cpu – CPU performance test
• memory – Memory functions speed test
• threads – Threads subsystem performance test
• mutex – Mutex performance test

As you can see, sysbench lets you stress many of the fundamental components of your hardware and infrastructure, such as your disk subsystem, along with your CPUs and memory. An additional option exists that is designed to perform synthetic stress testing of MySQL, and I was surprised when I didn’t see it in the above list on version 0.5, as it used to show up as “oltp – OLTP test”. What happened to –test=oltp …

很久之前看过这个帖子,当时没有细究,这几天看了下mysql相关的internal 突然想起这个问题,跟三四个朋友讨论了下 想把这个问题展开讲一讲。

源帖子内容见：https://community.oracle.com/thread/1087650?start=0&tstart=0

这个帖子的内容为一个老外问oracle如何避免partial write的,也就是大家所说的半个IO问题,IO 在写到一半的时候发生断裂,（瞬间断线,瞬间crash瞬间存储或者机器故障等） 虽然这个情况极少发生,但是在非常规恢复的时候也是经常遇到的,例如某个block内部出现不一致,也就是我们所谓的逻辑坏块。
我仔细的又过了一遍帖子,发现下面的几个回答完全不准确,或者有点张冠李戴的意思。

首先我们看看什么是mysql 的double write:

—–引自 …