Want to get an idea of what speed advantage adding an expensive hardware RAID card to your new server is likely to give you? You can benchmark the performance difference between running a RAID using the Linux kernel software RAID and a hardware RAID card. My own tests of the two alternatives yielded some interesting results.

The Ubuntu Live CD installer doesn't support software RAID, and the server and alternate CDs only allow you to do RAID levels 0, 1, and 5. Raid 10 is the fastest RAID level that also has good redundancy too. So I was disappointed that Ubuntu didn't have it as a option for my new file server.

RAID stand for a redundant array of inexpensive disks, a way of combining multiple disk drives into a single entity to improve performance and/or reliability. There are a variety of different types and implementations of RAID, each with its own advantages and disadvantages.

I was already mourning the destruction of my Saturday, thanks to some blown deadlines, and was resigned to spending at least part of the day working. Then I made a fatal error: I read my email. There were two messages from readers that said, in essence, another article about RAID 5 was about as interesting as yet another fawning review of Ubuntu Retching Rabbit or Pooping Penguin or whatever the newest coolest release is, and RAID 5 has some serious flaws anyway, and if I really wanted to be hip and helpful I would write about RAID 10.

Linux comes with software-based RAID that can be used to provide either a performance boost or add a degree of data protection. This article gives a quick introduction to Linux software RAID and walks through how to create a simple RAID-1 array.

I decided to buy two 80Gb drives and configure them in RAID-1. RAID-1 gives you mirroring and only requires two drives. RAID-5, for example, requires at least three. Now, I haven’t configured a RAID system for a while (five years?) and I was surprised at how easy Linux makes it.

RAID 1 is usually implemented as mirroring; a drive has its data duplicated on two different drives using either a hardware RAID controller or software (generally via the operating system). If either drive fails, the other continues to function as a single drive until the failed drive is replaced.

This short guide explains how you can configure software RAID to send you an email when something's wrong with RAID, for example if a hard drive fails. I've tested this on Debian Etch, but it should apply to all other distributions with minor adjustments to paths, etc.

I have benchmarked various Linux filesystems using different blocksizes and workloads on an mdadm RAID 1 setup using two Western Digital 500 GB SATA 3.0 drives and a 3ware 9550XS 4-port hardware RAID card (which I had trouble getting to work initially). It's not as extensive as I would have liked, but I came across some interesting results.