Webmaster in a Nutshell, Second Edition

Keep HTML Content and HTTP Logs on Different Disks

For the best performance, your web server should have at least two disks: one for content and the OS, and another one for web server logging. The reason is that accessing content causes essentially random disk access, while writing to the log file causes the disk arm to move sequentially. If you keep the log file writes sequential by confining them to their own disk, they’ll be very fast. Another reason to keep logs on another disk is to keep the system from crashing if the log file grows to take essentially the whole disk before being truncated or reset by the system administrator. You can also increase performance further by using another disk for your swap space. While you’re at it, consider yet another disk for the operating system itself because it has its own disk-usage patterns.

If you have separate disk controller cards for all these disks, their operations can proceed in parallel. If you use a single controller for several disks, make sure it has a maximum transfer rate equal to or better than the sum of the maximum transfer rates of all the disks connected to it.

Solid-state disks are now on the market. These disks use nonvolatile memory—either “flash” RAM or battery-backed RAM—but use a SCSI or other disk interface and so appear to the system to be an ordinary disk. There are no moving parts, so they are quite unlikely to ever break, unlike ordinary disks. Access time is thousands of times faster than rotating physical ...