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Don’t let the OOM killer stop MySQL
Many of our customers are successfully using MySQL (or MariaDB) databases on their servers, and they usually run fine as installed and do not need any special attention. However, occasionally problems can occur with MySQL, and this may indicate that some manual tuning is required. One scenario is when the system is short of memory,…
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MySQL replication and verification
We have a number of customer using MySQL replication. For the uninitiated, replication copies changes from a master server to a number of slave servers. This makes scaling your service mush easier and helps improve redundancy and failover. An introduction to setting that up is available in our Mysql Replication guide. Once you have replication…
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How to restore a WordPress site after hacks or exploits in 10 easy steps
A lot of people use WordPress, and seemingly a lot forget to click the upgrade button regularly enough and find they are exploited. In an ideal world, you would click that button whenever you see it needs updates, and have copious amounts of good backups. However, sometimes these things do not happen, and you need…
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Using perror to explain mysql error codes
A customer came to us with a problem copying one database to another, and requested we do it for him. Once we logged in we saw the error fairly quickly ~# mysqldump -uadmin -p`cat /root/.mysqlpass` database >dbdump.sql mysqldump: Got error: 29: File ‘./database/tablename.MYD’ not found (Errcode: 24) when using LOCK TABLES ~# It can be…
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Mysql Master/Master Replication & File sync for quick easy scaling or load balance
A lot of our customers often need a quick easy way to scale up without moving to a new host or changing IP, or even just want an overseas copy of their site, so this is a brief tutorial on how to duplicate your server, and have the database and files replicate between the 2…
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Building database clusters with MySQL
MySQL is a mainstay of many web based applications, and is popular with lots of our customers. There does comes a time when a single database server is not enough. To enhance redundancy MySQL has a couple of options. You can add more servers with vanilla replication enabled. Or you can look at setting up…
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Storage Clustering Part 1: An Introduction
John and I have recently been looking at server clusters, and how they can be provisioned to best fit our customers needs. This post is the first in (hopefully) a series on the results of that research. To start with in this post I would like highlight some common questions about big storage options. If…
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Setting up Monit + with tomcat
We get asked a lot by customers to install and setup monit. Its not an overly hard task, in fact its pretty darned easy. Monit is brilliant for monitoring and restarting services when they are down, it can alert you or just restart after 5 failed connects/attempts. It handles everything from disk space, to memory,…
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Failover – What happens when your VPS goes down?
A lot of customers are realizing that having 1 single VPS is great, but if for some reason it goes down and crashes, customers are left wondering what happened. Whilst rimuhosting monitor long term excessive CPU useage, it might be an hour before we realize a VPS has had an OOM error (out of memory)…
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wordpress & wordpress MU mass upgrade script 2.9.2
Okay, I have rolled the usual ‘upgrade all instances of wordpress’ script. In this version i finally got around to checking the permissions prior to updating and changing the ownership of them back to that owner afterwards. This was breaking things and could be rather annoying before if you had more than 5 sites to…