The Linux filesystem is logically one large directory structure. In a default install of SLES, unless otherwise specified, the entirety of the file structure is placed on a single disk partition. Because the / partition is the parent to all other portions of the filesystem, it is called the root. When a system is originally installed, the root is populated by directories only. The following directories are present by default: Athena:~ # ls / . bin dev home media opt root srv tmp var .. boot etc lib mnt proc sbin sys usr In Linux, you can add additional disk capacity to a system. To do this, you attach the new disk by mapping its contents into the directory tree and providing a unique directory from which it can be accessed. This directory is called a mount point. Adding disk capacity is identical to adding removable media to the system and temporarily associating it with the /mnt directory. In the case of a permanent mount, the disk information is associated with the mount point in /etc/fstab. In essence, any directory on the system can be associated, either temporarily or permanently, to additional storage. The root of the filesystem is bound to the selected target disk at install time. All the other directories under the root, however, are considered not only directories but possible mount points. In Chapter 2, "Updating the Server," we discussed the addition of extra storage and how it was possible to migrate the contents of /home and /srv from simple directories and convert them to individual disk partition mount points. Table 7.2 lists the directories in the root and summarizes their purpose.
All these mount points are candidates for conversion to separate physical devices. It is important to note that if the root partition becomes full, the system will no longer be able to log activity or create any temporary files and will simply cease functioning until it can resume these two tasks. It is therefore imperative to prevent this from happening by segregating the more dynamic directory structures, such as /srv, /var, and /home, onto separate physical partitions. Segregating the structures alleviates disk space contention on the root volume. As the system matures, growth of the individual mount points will also be easier to monitor. |