Before we get onto setting up RAID lets look at the other player in the storage subsystem game.
The filesystem determines how information is written to your drive. Filesystems are responsible for providing features such as security, data recovery and, of course, performance. If you've been a geek since the days of DOS, you've no doubt noticed that DOS and Windows 95 and its successors seem to have considerably faster disk access than Windows NT and Windows 2000. The FAT filesystem used by DOS and Windows 95 et al is a very simple filesystem which sports the following: it's terribly featureless, and it's fast. By contrast, the Windows NT/2000/XP filesystem NTFS provides all manner of features such as security and data recovery, but is clunky and slow. This is the standard payoff between features and speed.
The Linux Ext2 filesystem has many features similar to NTFS, and is slightly faster. FAT remains, however, the fastest filesystem in use today — at least for small to medium-sized drives. After a certain limit (supposedly around 8G, but effectively closer to 4G) FAT starts to slow down rapidly — it's not designed for large filesystems.
Ext2 has been the standard Linux filesystem for some time, but it's not the only one available. One feature that many high-end Unix systems have is a journaiing filesystem. Without going into the computer science theories behind filesystems too much, a journaiing filesystem is one which keeps a journal of access requests that's written before the requests themselves are carried out. Why is this handy? Have you ever turned off Linux without shutting down and been forced to sit through an Ext2 filesystem check that's taken minutes to complete (or considerably longer for large drives and slow systems)? Wait no more; with a journaiing filesystem a sudden crash or reboot can be recovered from in seconds.
During reboot, if the filesystem detects that it wasn't shut down properly, it will 'replay' the journal and carry out any requests it didn't have a chance to complete. This takes less than a few seconds, after which the integrity of the filesystem is restored. Moreover, this journaiing feature means that it's very rare to lose any information from a sudden shutdown. And, if that weren't enough to convince you to install a new filesystem, journaiing filesystems are also quite fast (faster, at least, than Ext2).
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