Systems Administration

February 2019 Server Parts Pricing Report

Another month has gone by, and it’s time for the second installment of our monthly server parts pricing report. You may have seen the wild price fluctuations on RAM and SSDs the last year or so. As well, some models of really powerful CPUs have come way down on the aftermarket. It can be a

January 2019 Server Parts Pricing Report

First update in a while, but I think this is a good one. You may have seen the wild price fluctuations on RAM and SSDs the last year or so. As well, some models of really powerful CPUs have come way down on the aftermarket. It can be a lot to keep up with. Along

What is RAID 0? — RAID striping explained

RAID – or “Redundant Array of Independent Disks” – is a strategy for data storage used on most server setups. Understanding how RAID works, how it can help you meet the needs of your business or organization, and understanding differences between RAID levels is important before setting up your server. This article discusses RAID 0

What is RAID 5 — RAID parity explained

It’s hard to talk about servers without RAID coming up. If you’re considering RAID for your server and want to know if RAID 5 is right for you, or if you just want to learn more about RAID in general, you’ve come to the right place. We’ll go over that and more in this article.

What is RAID 10 — Nested RAID levels explained

RAID is a topic that comes up a lot when discussing servers. If you’ve wondered what RAID is, why you might want it on your server, and whether RAID 10 is the best option for you, look no further. We’re going to be discussing all of that in today’s article. What is RAID? RAID, or

Adding AHCI support to CentOS after it was already installed in IDE mode

Sometimes when you’re using a server, you’ll notice that the disk i/o is slower than it ought to be, or is using a lot more cpu than it should be during disk i/o. In some cases, this would be because the BIOS is configured to use your sata drives in legacy IDE mode instead of

Setting up Software RAID / MDADM status alert Emails for failed drives in Centos, Ubuntu, and Debian

Issues regarding software and hardware raid are no stranger to the IOFlood blog, with articles discussing the relative merits of each, articles discussing why raid is important (and so are backups), and so on. But RAID only provides protection against failed drives if you realize a drive has failed and replace it. Often times, a

How to set up source nat routing (SNAT) in iptables to load balance outbound connections across multiple IP addresses

In our earlier days, before IOFlood, some of us ran web based proxy services. These were popular at workplaces or schools for accessing websites that were blocked there, such as gmail and myspace (remember myspace?). One common problem that came up, was that with so many users each sharing one IP on one server, our

Making sense of Linux memory usage, Part 1: how to read “top” in CentOS.

We get this question a lot, about “Why is my Linux server using so much ram?”. In many cases, it really isn’t using much ram at all, but just to be sure we always have to check. At least half the time, really very little is being used, but the way that Linux reports ram

Configuring additional IP addresses (virtual interfaces) on Centos Servers

You may have a Centos dedicated server or VPS, and you’ve been assigned additional IP addresses, which have not been configured by your hosting provider. There are good reasons your host won’t have configured these for you, because if you are using virtualization, many VPS control panels need to manage these IPs, and so it