5.6 Concluding Thoughts

We've discussed most of the major issues surrounding I/O performance tuning: the basic concepts of disk drives , such as physical layout, access patterns, and the parameters that govern disk performance; the interfaces that communicate with those disks; various types of filesystems; and the tools that monitor the performance of our disks and I/O subsystems.

In many ways, disks occupy a unique pedestal in the field of computer architecture; they are the only portion of a system whose operation relies upon mechanical parameters and moving parts, and they are the last resort for online information storage. This realm is without the glamour of microprocessor design, where every cycle counts, and it is not one of the most fundamental parts of modern computer design, like memory. Perhaps for these reasons, it is one of the areas most commonly disregarded by systems administrators when approaching performance tuning problems.

Disk tuning is like a dark lake in the middle of a forest, filled with all manner of strange and wonderful things; it doesn't seem to hold much beauty, and it can even be a bit foreboding. But there are pearls of great performance worth just a few feet below the surface of that lake -- seize the chance to find a few.