Managing RAID on Linux

Chapter 6. Filesystems

Choosing and properly configuring a filesystem is as important as selecting an appropriate RAID level. ext2 (the Second Extended Filesystem) is the standard Linux filesystem. Many users will be perfectly happy using ext2; it is reliable and can be fine-tuned to meet specific demands of file usage. But while ext2 might be suitable for end users, it doesn’t fare as well for large, heavily used filesystems that have extremely large files or thousands of small files. ext2 doesn’t provide any way to maintain filesystem integrity through system crashes. Also, ext2 is slowly making way for ext3, a journaling filesystem that I’ll cover later in this chapter. Maintaining data integrity and availability has become an essential requirement for all critical systems. After all, this is one of the most recognizable benefits of RAID. Fortunately, there are a wide variety of filesystems for Linux that implement crash recovery and prevention features. These systems are collectively called journaling filesystems, and their main distinction from traditional Unix filesystems is that they don’t require filesystem checks after a system crash. I’ll cover journaling in greater detail later in this chapter. Even if you aren’t interested in journaling filesystems right now, it’s a good idea to begin learning about them. It won’t be long before your need for increased data reliability or fast recovery may force you to make a change to a journaling filesystem.

There are several alternatives ...