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Displaying posts with tag: Linux (reset)
Ulimit conflict with PAM and Systemd​​​

As a part of the MySQL Support, we had a support request from a client.The issue is DB server runs out of open files limit, though it is configured. It causes the DB hang and crash at times. Sometimes they can’t able to fix. So we plan to write our experience with configuring. We believe this article can help in configuring appropriate Ulimit value without any obstacles. Let us jump to the subject. What are the errors we might face while ulimit is not properly configured?

  1. Too many open files
  2. System unable to allocate necessary resources for the monitor thread
  3. can’t create new thread, closing connection

The above-shared list is just sample’s, maybe people who currently reading this blog may also face issue related to ulimit, for that they may have different debug …

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Hands-On Look at ZFS with MySQL

This post is a hands-on look at ZFS with MySQL.

In my previous post, I highlighted the similarities between MySQL and ZFS. Before going any further, I’d like you to be able to play and experiment with ZFS. This post shows you how to configure ZFS with MySQL in a minimalistic way on either Ubuntu 16.04 or Centos 7.

Installation

In order to be able to use ZFS, you need some available storage space. For storage – since the goal here is just to have a hands-on experience – we’ll use a simple file as a storage device. Although simplistic, I have now been using a similar setup on my laptop for nearly three years (just can’t get rid of it, it is too useful). For simplicity, I suggest you use a small Centos7 or Ubuntu 16.04 VM with one core, 8GB of disk and 1GB of RAM.

First, you need to install …

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Docker Compose and App Deployment with MySQL

In this post we show how to use the mysql-server Docker image for local development. We first introduce a simple example app that starts up and tries to connect to a given db until successful. We then show how to start containers for multiple MySQL versions and use our example app to connect to them. […]

MySQL and Linux Context Switches

In this blog post, I’ll look at MySQL and Linux context switches and what is the normal number per second for a database environment.

You might have heard many times about the importance of looking at the number of context switches to indicate if MySQL is suffering from the internal contention issues. I often get the question of what is a “normal” or “acceptable” number, and at what point should you worry about the number of context switches per second?

First, let’s talk about what context switches are in Linux. This StackOverflow Thread provides a good discussion, with a lot of details, but basically it works like this:  

The process (or thread in MySQL’s case) is running its computations. Sooner or later, it has to do some blocking operation: disk IO, network IO, block waiting on a mutex …

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InnoDB Cluster: setting up Production… for disaster! (2/2)

Ok, so now we’re got our InnoDB Cluster a-clustering, MySQL Router a-routing, now we need some disaster to be a-disaster-recovering…

A foreword first.

If you’re looking to use Enterprise Backup to recover a single node and restore that node back into an existing InnoDB Cluster, LeFred takes you through that one nicely here.

Preparing for backup

On our single primary server, the one that allows write, which was ic2/10.0.0.12 in my case:

mysql -uroot -poracle << EOF 
SET sql_log_bin = OFF; 
 create user 'backup'@'%' identified by 'oracle';
 grant all on *.* to 'backup'@'%';
SET sql_log_bin = ON; 
EOF

Let’s create something to backup (if you haven’t already done so of course):

mysqlsh --uri …
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InnoDB Cluster: setting up Production… for disaster! (1/2)

Want to setup InnoDB Cluster and be prepared for a Disaster Recovery scenario? Get ready:

Here’s a way to set up InnoDB Cluster using the 3 environments, on Oracle Linux 7.2, 5.7.19 MySQL Commercial Server, MySQL Shell 8.0.3 DMR, MySQL Router. As this is the first blog post for a complete disaster recovery scenario of InnoDB Cluster, we’ll also be installing MySQL Enterprise Backup.

If you’re new to InnoDB Cluster then I’d highly recommend looking at the following to understand how it works and what Group Replication, Shell & Router are.:

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Install Nginx, MariaDB and PHP (FEMP stack) on FreeBSD 11

In this tutorial, I will describe the process of installing and configuring the FEMP stack on FreeBSD 11.x. FEMP software stack is an acronym for FreeBSD - Nginx - MySQL (or MariaDB) and PHP.

On Open Source Databases. Interview with Peter Zaitsev

“To be competitive with non-open-source cloud deployment options, open source databases need to invest in “ease-of-use.” There is no tolerance for complexity in many development teams as we move to “ops-less” deployment models.” –Peter Zaitsev

I have interviewed Peter Zaitsev, Co-Founder and CEO of Percona.
In this interview, Peter talks about the Open Source Databases market; the Cloud; the scalability challenges at Facebook; compares MySQL, MariaDB, and MongoDB; and presents Percona’s contribution to the MySQL and MongoDB ecosystems.

RVZ

Q1. What are the main technical challenges in obtaining application scaling?

Peter Zaitsev: When it comes to scaling, there are different types. There is a Facebook/Google/Alibaba/Amazon scale: these …

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Protocol reverse engineering with tcpdump

Sometimes network protocols don’t entirely behave as documented. Other times there is no documentation at all beyond code. Either way you can sometimes find a need to sniff the traffic of a connection to find out what is really going on.

Whilst I have been working on MariaDB ColumnStore for a year now there are still some parts of the codebase I know little about. I recently had to write some code that worked with the network protocol of ColumnStore, but there were a few parts that were difficult to understand exactly what was happening just by looking at the code. This is where tcpdump came in.

tcpdump is a powerful tool to help you sniff the raw packet data for network connections. It can be very verbose giving parts of the TCP/IP handshake, headers, etc… This is way more than I often need …

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MySQL Support for Fedora 26 Is Here

Fedora 26 is scheduled to arrive today, July 11, and we congratulate the highly productive Fedora community on another rev of many people’s favorite distro. We’re continuing our tradition of supporting new distro releases from day one, and Fedora 26 users will find the following MySQL products in the official MySQL yum repos: MySQL Server […]

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