There are few ways to get a flame war going faster than to ask a Linux user which file system is the best? While many will argue in favor of one of the iterations of Ext: Ext2, Ext3, or Ext4, others will get more creative, promoting file systems such as ReiserFS, XFS, ZFS, and countless others. Before you decide to invest in any particular file system, there are few things you should know.
Ext2 is a great file system that was used for many years on countless Linux machines without problems. Nevertheless, it has begun to show age, and Ext3 added features, such as journaling, that allow for much easier recovery in the event of a crash. Ext4 takes that a step further by also providing a significant performance boost.
Ext2 does have some benefits in that it writes to disk a lot less frequently than Ext3. That makes it ideal for flash drives, which can only stand a limited number of writes. Therefore, if you are using flash cache or solid state drives on your server, you may benefit from using Ext2 on that hardware, but you could also use Ext4 and simply disable journaling, while benefiting from the performance boost.
Finally, it is worth noting that other file systems, such as ReiserFS and XFS also include journaling and many other useful features. To choose the best one for your server, you should consider both the features and the level of compatibility and performance that each file system would have on your hardware and with your applications.