Hands on: Get to grips with Raid

Raid issues
One issue to be aware of when implementing any type of Raid is how easy the array is to transport. Users of single hard disks are used to being able to connect them to any other system and immediately access the data.

This is because basic hard disk controllers are compatible with each other.

A Raid array also requires a compatible controller to operate, but many are proprietary and you may need one from the same manufacturer, or even an identical chipset to that which originally created the array.

Clearly problems can occur if you can’t find a compatible replacement. In this worst-case scenario you wouldn’t be able to access your array or the data.

Separate controller cards are often more flexible than integrated motherboard chipsets. You’re not putting all your eggs in one basket and, so long as your array’s not the boot volume you should be able to remove the disks and card and connect them to a different system to access the data.

Another lesser, but annoying issue that affects all types of Raid is the requirement to install a driver for the controller.

While this may easily be done under Windows when adding Raid to an existing system, anyone who wishes the array to be their bootable ‘C’ volume will need the driver on a floppy disk for use during Windows’ Setup.

To be fair, this also applies to less common SCSI and serial ATA (Sata) controllers, but it’s still highly inconvenient to require access to a floppy drive in this day and age.

It’s worth mentioning that Raid arrays with their multiple hard disks make more noise, consume more power and occupy more space than a single disk.

This makes them better suited to a server-type machine in a back room rather than a standalone entertainment PC in your main living area.

Raid in practice
Since a Raid array is limited by the lowest capacity and slowest disk in the array, it’s best to use identical drives.

So to put various Raid options to the test we bought three Seagate 300GB 7200.9 Sata disks (pictured below left); at the time of writing the 300GB models represented good value per GB.

For flexibility we fitted these to a separate Raid controller card: a Promise Fasttrak TX4310 which includes support for Raid 0, 1 and 5 on up to four Sata disks.

For ease of installation and transportation, we implemented our Raid arrays as secondary storage volumes on a 2.13GHz Pentium M 770 system with an existing boot drive. The TX4310 then needed only a Windows driver to be operational.

Like many Raid controllers, the TX4310 can either be configured at the Bios level as the machine starts up, or using a web-based management system under Windows.

Using either it’s simple to configure any connected disks into a Raid array. The process takes a matter of seconds, after which you should use Windows’ Disk Management tools to partition and format the volume as if it were a single disk.

Since Windows XP Pro offers software Raid, you should only ‘Initialise’ the new volume and skip the option to ‘Convert’ it.

We tested the system with three Raid configurations: Raid 0 and 5 with three disks each, and Raid 1 with two disks as it only works with pairs. In each case the stripe block size was set to the default 16KB. Onto each array we copied 20GB worth of Media Center recordings.