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Showing entries 1 to 30 of 30

Displaying posts with tag: Redhat (reset)

Increasing MySQL 5.5 max_connections on RHEL 5
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Busy database-backed websites often hit scalability limits in the database first. In tuning MySQL, one of the first things to look at is the max_connections parameter, which is often too low. (Of course another thing to look at is appropriate fragment caching in your app server, HTTP object caching in your web server, and a CDN in front of it all.)

When using MySQL 5.5 from Oracle's RPMs through cPanel (MySQL55-server-5.5.32-1.cp1136) on RHEL 5.10 x86_64, there is an interesting problem if you try to increase the max_connections setting beyond 214 in /etc/my.cnf. It will silently be ignored, and the limit remains 214:

mysql> show variables like 'max_connections';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| max_connections | 214   |
+-----------------+-------+
1 row in set (0.00 sec)

The problem is

  [Read more...]
MySQL RPMS and the new yum repository
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I was really pleased to see the announcement by Oracle MySQL yum repositories that they have now produced a yum repository from where the MySQL RPMs they provide can be downloaded. This makes keeping up to date much easier. Many companies setup internal yum repositories with the software they need as then updating servers is much easier and can be done with a simple command. For many people at home that means you set this up once and don’t need to check for updates and do manual downloads, but can do a quick yum update xxxx and you get the latest version. Great!  This new yum repository only covers RHEL6 did not include RHEL5 which is not yet end of life and still used by me and probably quite a lot of other people. I filed

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On operating system upgrades and a packager’s nightmare
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A fairy tale

Once upon a time I did an operating system upgrade, a minor one that should do no harm, but just get me up to date by fixing any bugs in the version I had been using. It seemed like a good idea.

All seemed to be fine. I use a package provided by an external vendor and not the one produced by the operating system provider as this vendor provides a newer version of the package and I need that. The vendor has to make his package fit in the os environment his package is built for and normally does a pretty good job.

I use automation to build my systems and when I built a new one some issues appeared. Related to the new version of the OS the provider had enhanced one of his packages and the installation pulled in new dependencies. The install of the external package I use then broke as it conflicted with the new dependency

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MariaDB replaces MySQL in RHEL7
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Subject says its all, this is of course, very good news coming out of the Red Hat Summit. Looking forward to Red Hat Enterprise Linux 7. And of course, CentOS 7 and the other builds that follow. Thank you Red Hat!

MariaDB replaces MySQL in RHEL 7. Glad to see that. #rhsummit

— Major Hayden (@majorhayden) June 12, 2013

at #rhsummit , rhel7 will come without mysql as it will be replaced with mariaDB; which is mysql api compatible. it will include mongodb too

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How to fix the Percona repo failure when installing Percona Toolkit
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Here’s a solution to the not-so-long-standing issue of the Percona yum repo being broken for the CentOS 6 x86_64 version of the Percona-toolkit package. The repo listing is reporting an older version of the RPM which is not available on the site, so to fix this you just have to download the newer file and tell yum to add it locally. The side benefit is that you can use Yum to manage the RPM without adding the Percona repo, since the default settings for their repo could/have/had caused conflicts with Base Repo versions of MySQL packages; the Percona repo instructions set ‘enabled=1′ — not a great idea if you’re not setup to use the Yum priorities method of repo weighting.

So, if you see this after installing the repo via the instructions on their site:
Downloading Packages:


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Serious XFS Performance Regression in Linux Kernel 2.6.32-279
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I'm not the only one to have noticed this, but I spent a sufficient amount of time banging my head against a wall finding this out that I thought it important to make more people aware of this.

While trying to validate new database hardware we were seeing some serious performance issues in production.  Most MySQL benchmarks using sysbench or pt-playback couldn't reproduce it, but a simple sysbench 16 threaded filio test on the mysql partition showed about 1/3 the throughput we would expect.   The fact that much of the hardware was new as well as the OS we were using made tracking down the cause difficult (changing from CentOS 5.5 to Scientific Linux 6.)

Finally some of our ops people working on different systems started noticing similar issues, and they uncovered the XFS issue.  Sure enough -- when took existing hardware,



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How do we control MySQL daemon in Linux, part1
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As you may expect from open source world thingy, almost every Linux distribution has developed it’s own way to manage our favourite RDBMS service. Yet none is perfect, or even some of them seems to not work in real server scenario1.

In this post I’m trying to compare and point out most annoying aspects of initialization scripts that I had to face in production.

In ‘old days’ probably all Linux distributions used to start and stop services using so called init scripts usually written in Unix shell (sh or Bash). But situation is not so simple these days anymore.

Folks started to think about improving things, like making

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Open Query looking for new colleagues!
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My colleagues and I are looking for extra talent – is that you? What we do:help clients prevent problems (rather than being the fire department), we work on a subscription basis although we also do some ad-hoc consulting, and training. Apart from MySQL/MariaDB query and DBA work, we do quite a bit of system administration. Mainly Red Hat and Debian based distros, and expect to see replication and the MySQL-MMM multi-master system. You’d work from home, whereever it might be, so you will need to be self-motivating (but we do keep in touch online). What we’re not: a full-time employer. With us, you make a life rather than a living. Everybody is contracted part-time. You can make enough to live comfortably, but that has nothing to do with hours. If you’re stressed about not filling all hours in your week with work-work-work, we’re not  [Read more...]
MySQL Clusters in the Cloud with Severalnines on OpenShift
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A blog post on how to deploy a sample JBoss application on OpenShift Flex - using a highly available, scalable backend that leverages MySQL Cluster

The Severalnines team has been busy during the summer months and as result, we have included OpenShift Flex support to our Severalnines Configurator (amongst other things). OpenShift, a Platform-as-a-Service operated by Red Hat, allows developers to develop and manage applications in the cloud. It is now possible to configure a clustered MySQL database for cloud services running on OpenShift. This brings high-availability and scalability at both the application and database layers.

As a guest contributor



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MariaDB 5.2 repository for RHEL/CentOS
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Until now, MariaDB 5.2 was lacking a yum repository for easy installs and upgrades. It is now available, thanks to OurDelta.

Just follow our very simple installation instructions.

MySQL HA with DRDB and Heartbeat on CentOS 5.5
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This is one of a few MySQL High Availability strategies.  I have used this for years and found it work great.  If you don’t know about DRBD and MySQL you should read Peter’s comments.

These are step by step instructions for Redhat 5 or CentOS.

If you need more details please refer to:
http://www.drbd.org/users-guide/

Configuring MySQL for DRBD
http://dev.mysql.com/doc/refman/5.1/en/ha-drbd-install-mysql.html

Getting started:

The OS in this example is CentOS 5.5.  I added a new disk (/dev/sde) to the four disk RAID-5 and RAID-1 I was already using.   I’m only



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How to install MongoDB on CentOS 5.4 / RHEL5 and interface with PHP 5
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If you’ve been reading up on the various NoSQL offerings and have wanted to try out one but don’t know how to get started, this is one of the easiest ways. I chose MongoDB for this example because I’m going to start using it for a project that needs features that MySQL isn’t as fast at: namely denormalized data with billions of rows. MongoDB has plenty of drivers for other scripting and high-level languages but I’ll focus on the PHP driver today. If there is interest I can do a write up on Python usage later. This example is limited to CentOS, Fedora, and Redhat 5 servers that use the yum package management system. For more information you can reference their download page: http://www.mongodb.org/display/DOCS/Downloads

First install the prerequisites:

  • sudo yum
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Install MariaDB on RedHat 5.4
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Tweet

Is MariaDB really a drop in replacement for MySQL?   I’m running CentOS 5.4.  What happens if…

  • Use “mysqldump –all-databases > FullBackup.sql” to make a full backup. (Better safe then sorry)
  • Go to http://askmonty.org/wiki/MariaDB:Download and download the CentOS 5 packages.
  • Stop msql “service mysqld stop”
  • Pull MySQL out by the roots with “rpm -e mysql-server mysql –nodeps”
  • Install Maria with “rpm -i Maria-*”
  • And the install start mysql up again.  Wow.  That’s “Drop in”.

    If your

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    MySQL Ruby Gem CentOS RHEL 5 Installation Error Troubleshooting
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    Building and installing the Ruby mysql gem on freshly-installed Red Hat based systems sometimes produces the frustratingly ambiguous error below:

    # gem install mysql
    /usr/bin/ruby extconf.rb
    checking for mysql_ssl_set()... no
    checking for rb_str_set_len()... no
    checking for rb_thread_start_timer()... no
    checking for mysql.h... no
    checking for mysql/mysql.h... no
    *** extconf.rb failed ***
    Could not create Makefile due to some reason, probably lack of
    necessary libraries and/or headers.  Check the mkmf.log file for more
    details.  You may need configuration options.
    

    Searching the web for info on this error yields two basic solutions:

  • Install the mysql-devel package (this provides the mysql.h file in /usr/include/mysql/).
  • Run gem install
  •   [Read more...]
    Understanding installing MySQL rpm versions
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    I have a problem with an easy way to install MySQL via rpm without resorting to specifying the exact point release of MySQL. Presently my local yum repository has versions of 5.0, 5.1,5.4 and 5.5.

    If I want to install MySQL Sever, I can just run:

    $ sudo yum install -y MySQL-server
    Setting up Install Process
    Package MySQL-server-community-5.5.0-1.rhel5.x86_64 already installed and latest version
    Nothing to do
    

    The issue here is the most current version is installed. If I want to install the most current version of 5.1 for example, I have found no way to specify MySQL-server-5.1, or MySQL-server-community-5.1, I have to specify the point release MySQL-server-community-5.1.40

    I suspect there is some internal aliasing that may be possible within rpm’s to support this. I’m seeking help from any rpm experts and would

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    MariaDB 5.1.39 for Debian, Ubuntu, RHEL/CentOS
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    You can now yum (RPM) or apt-get (DEB) MariaDB 5.1.39, courtesy of OurDelta and in close cooperation with Monty Program Ab. Simply follow the info on the CentOS, Debian or Ubuntu pages.

    (note: give the mirrors some hours to sync up)

    Quick overview

    • See the Release Notes for relevant bugfixes.
    • Drop-in replacement for stock MySQL 5.0 or 5.1 (If you’re coming from stock MySQL, see the MariaDB extras/differences overview).
    • If you are upgrading from 5.0, please review the
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    MySQL 5.0.87-d10 OurDelta packages
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    MySQL 5.0.87-d10 OurDelta builds are now available (32 and 64-bit):

    Apart from the 5.0.87 upstream fixes there were a few minor fixes in the build environment, and one updated Percona patch. The -sail builds now include the OQGRAPH engine. Source packages are with the respective distro repos, and there are base source  [Read more...]
    Let the customer choose where to buy lunch from !
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    Matt Asay is pushing his favorite Open Source model again. The model where the majority of developers of a project work for a company and that company is creating a business around the project. There's nothing wrong with that model, but he seems to forget the other models time over time :)

    Matt is absolutely right with 2 of the 3 things he wants you to consider.
    A SI in the middle of a $50 million dollar project involving Alfresco not talking to Alfresco is just wrong. An SI not offering a support contract is also just wrong. But an SI forcing his customer to buy the commercially supported version from a vendor ? Where's the customer choice ?

    The customer should have the option to choose for a commercially supported version or the free version. And preferably that should be an educated option.


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    sshfs: How do you install sshfs and fuse? [CentOS/Linux/Redhat]
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    One may wonder what is sshfs and why would you want it?  Well simply put, sshfs allows you to mount another server’s filesystem into a folder on your local system which in the background is doing ssh commands and transfers.  As a mounted folder, you are able to move about and copy files back and forth as everything was on local server.  As you can see this makes it very easy for you to work with files on multiple servers.

    Note:  you only have to do the following installations on the server where you are doing the mounts on.

    Let us download and install the filesystem framework which is a requirement for sshfs called fuse.

    wget http://voxel.dl.sourceforge.net/sourceforge/fuse/fuse-2.7.4.tar.gz
    tar zxpfv fuse-*.gz
    cd fuse*
    ./configure

    If you get the following error, you will either have to point to the location




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    MySQL: How do you enable sphinxse (Sphinx Storage Engine) in your mysql installation?
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    As you may know mysql fulltext search is not highly scalable.  One of the options to get around this scalability limitation, which I prefer, is to use Sphinx.  You can use Sphinx with out having to alter your mysql installation.  But, if you would like to use from within mysql and not have to worry about how to pass data between Sphinx and MySQL, you can enable sphinxse (sphinx storage engine).  It is not included with mysql by default so you will have to compile it yourself.

    Here are the instructions on how to get sphinxse compiled with your mysql installation on CentOS x64.  I am sure same instructions will work for other flavors but I have not tested it.  I will be compiling the most current version of sphinx (0.9.8) with most current stable version of mysql (5.0.51b) at the time of the writing.  Let’s get the

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    Spacewalk, and what we can learn about naming
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    Red Hat releases Spacewalk. It is described as: “the upstream community project from which the Red Hat Network Satellite product is derived“. Congratulations to all whom have worked on it, especially my friends who tired endlessly over it in the past.

    Red Hat, is sticking true to its promise, of open sourcing everything they make. Best of all, they recognise Fedora (they always did, since say, Fedora Core 2 or 3), CentOS (a direct “competitor”/rebuild of RHEL), and Scientific Linux (I know of a certain university’s sysadmin who will be blessing Spacewalk, as her life will now be a lot easier).

    There have been a few blogs about it… Matt Asay asks about a community (Red Hat traditionally

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    Linux: yum options you may not know exist.
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    Most of the users who work with distributions such as: centos, fedora, redhat, etc use yum as a package update/installer. Most of them know how to do “yum update [packagename]” (to update all or [certain packages]) or they do “yum install packagename” to install certain package(s). But yum can do so much more. Here are some options you may find useful:

    Following command will search for the string you specified. Generally this will give you all of the packages which has specified string in title or description. Most of the time you will have to look through a lot of output to find what you are looking for.

    yum search string

    Probably one of the most important options for yum is provides/whatprovides. If you know what command you need, you can find out what package you have to install in order to have that command available to

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    Open Source Day, Rome - June 10, 2008
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    With a few days of delay, I want to share my impressions about Red Hat's Open Source Day presented in Rome on June 10, 2008.

    The Event

    Event was organized really well, Red Hat took responsibility of everything and all went smoothly toward the end. There were more than 200 attendees and the hall was crowded of Open Source enthusiasts, customers and others waiting for interesting speeches and a juicy agenda. General impression was very good, a lot of attention from both community attendees and customers willing to deeper their Open Source knowledge and listening to shining or emerging stars in the field.

    A rich agenda gave everyone a bunch of new ideas to think about.

    MySQL/Sun

    Luca Gargaglione catalyzed attendees attention by explaining How and Why MySQL



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    Open Source Day, Rome - June 10, 2008
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    With a few days of delay, I want to share my impressions about Red Hat's Open Source Day presented in Rome on June 10, 2008.

    The Event

    Event was organized really well, Red Hat took responsibility of everything and all went smoothly toward the end. There were more than 200 attendees and the hall was crowded of Open Source enthusiasts, customers and others waiting for interesting speeches and a juicy agenda. General impression was very good, a lot of attention from both community attendees and customers willing to deeper their Open Source knowledge and listening to shining or emerging stars in the field.

    A rich agenda gave everyone a bunch of new ideas to think about.

    MySQL/Sun

    Luca Gargaglione catalyzed attendees attention by explaining How and Why



      [Read more...]
    Open Source Day, Rome - June 10, 2008
    +0 Vote Up -0Vote Down

    With a few days of delay, I want to share my impressions about Red Hat's Open Source Day presented in Rome on June 10, 2008.

    The Event

    Event was organized really well, Red Hat took responsibility of everything and all went smoothly toward the end. There were more than 200 attendees and the hall was crowded of Open Source enthusiasts, customers and others waiting for interesting speeches and a juicy agenda. General impression was very good, a lot of attention from both community attendees and customers willing to deeper their Open Source knowledge and listening to shining or emerging stars in the field.

    A rich agenda gave everyone a bunch of new ideas to think about.

    MySQL/Sun

    Luca Gargaglione catalyzed attendees attention by explaining How and Why



      [Read more...]
    Linux: How do you rename a user account in linux?
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    In Linux, there is no command which will rename a user account. If you make a mistake creating a user account, user changes their name or if user does not like his user name, there is no real easy way of going and making the change. Only thing I know you can do is to go through some files and rename user manually. Let us say that we have a user who is named joe and we want to rename him to john.

    Note: you must be logged in as root to do following.

    vi /etc/passwd
    find joe and change it to john, save/exit

    vi /etc/group
    find joe and change it to john, save/exit

    vi /etc/shadow
    find joe and change it to john. This file is read only and you have to force overwrite it. In vi it is :w! once saved, quit.

    cd /home
    mv joe john

    And that should do the trick.

    [Edited] Right after I posted this post, I was





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    MySQL: How do you set up master-master replication in MySQL? (CentOS, RHEL, Fedora)
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    Setting up master-master replication in MySQL is very similar to how we set up master/slave replication. You can read up about how to setup master/slave replication in my previous post: How to set up master/slave replication in MySQL. There is obviously pros and cons about using master/master replication. But this is not [...]   [Read more...]
    MySQL: How do you set up master-slave replication in MySQL? (CentOS, RHEL, Fedora)
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    Before we go into how to set up master-slave replication in MySQL, let us talk about some of the reasons I have set up master-slave replication using MySQL. 1) Offload some of the queries from one server to another and spread the load: One of the biggest advantages to have master-slave set [...]   [Read more...]
    PHP: How do I install phpsh, interactive shell prompt for php under CentOS or Fedora?
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    phpsh requires readline support built into python. It also requires python version 2.4+. You can check which version of python you have installed by typing: python -V Let us download and install readline: wget ftp://ftp.cwru.edu/pub/bash/readline-5.2.tar.gz tar zxf readline-5.2.tar.gz cd readline-5.2 ./configure make install Now let us install python with readline support: wget http://www.python.org/ftp/python/2.5.1/Python-2.5.1.tgz tar zxf Python-2.5.1.tgz cd Python-2.5.1 I had some problems on one of the [...]   [Read more...]
    MySQL: How do I import individual table dump files in to MySQL using shell script?
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    After I wrote the post: How do I dump all tables in a database into separate files? I got emails from couple people asking how to import the individual table files back in to MySQL. First way to import each sql file created by the post is to import each file individually by [...]   [Read more...]
    Showing entries 1 to 30 of 30

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