As part of my current research for upcoming setup, I started reading up on filesystems (was actually looking up fencing which leds to node crash and file integrity on different fs) to see if there would be any significant improvement to using a different filesystem for the glusterfs storage nodes. Initially, the reading suggested that ext4 would provide a significant performance boost. Quite possibly since it delays write longer, latencies of the network storage is hidden even better especially for temporary files. After subsequent reading, it seems that the cost of the massive delay allocation that could blow up really bad in the event the system crash. However, this may also be limited to poorly written applications, i.e. since some massive arguments last year over Firefox 3.0, sqlite and ext4 problems, ext4 now detects situations where it should flush to disk immediately to avoid zero length files on crash. Assuming I'm using the most likely disk writing applications I'm using is KVM, exim, dovecot, mysql and postgresql, would ext4 be safe for production use or should I stick to ext3?
