In most hosting environments, your entire virtual instance is mounted on a single drive of maybe 10-20GB in size. In self hosted or VPS solutions additional disks are often available and are usually mounted with default parameters. The default parameters commonly used when mounting a file system include the writing of the last access times to the file system for every file accessed, this is of little use on a production server and can be safely disabled.
If at all possible, turn off the atime and diratime parameters in /etc/fstab using the noatime and noadirtime flags on all relevant file systems. This will reduce writes to the file system when a file is accessed.
The addition of the two flags is made to the entries in the /etc/fstab file related to physical disks. The command line in your /etc/fstab file would look something like:
/var/www ext4 defaults,grpquota,noatime,nodiratime,data=ordered 0 0
This change will result in a tiny improvement in performance but every bit counts!