Like most other operating systems, LFS is usually installed on a dedicated partition. The recommended approach to building an LFS system is to use an available empty partition or, if you have enough unpartitioned space, to create one.
A minimal system requires a partition of around 2.8 gigabytes (GB). This is enough to store all the source tarballs and compile the packages. However, if the LFS system is intended to be the primary Linux system, additional software will probably be installed which will require additional space. A 10GB partition is a reasonable size to provide for growth. The LFS system itself will not take up this much room. A large portion of this requirement is to provide sufficient free temporary storage. Compiling packages can require a lot of disk space which will be reclaimed after the package is installed.
Because there is not always enough Random Access Memory (RAM)
available for compilation processes, it is a good idea to use a small
disk partition as swap space. This is
used by the kernel to store seldom-used data and leave more memory
available for active processes. The swap partition for an LFS system can be the same
as the one used by the host system, in which case it is not necessary
to create another one.
Start a disk partitioning program such as cfdisk or fdisk with a command line option
naming the hard disk on which the new partition will be
created—for example /dev/hda for
the primary Integrated Drive Electronics (IDE) disk. Create a Linux
native partition and a swap
partition, if needed. Please refer to cfdisk(8) or fdisk(8)
if you do not yet know how to use the programs.
Remember the designation of the new partition (e.g., hda5). This book will refer to this as the LFS
partition. Also remember the designation of the swap partition. These names will be needed later
for the /etc/fstab file.
Requests for advice on system partitioning are often posted on the LFS mailing lists. This is a highly subjective topic. The default for most distributions is to use the entire drive with the exception of one small swap partition. This is not optimal for LFS for several reasons. It reduces flexibility, makes sharing of data across multiple distributions or LFS builds more difficult, makes backups more time consuming, and can waste disk space through inefficient allocation of file system structures.
A root LFS partition (not to be confused with the /root directory) of ten gigabytes is a good
compromise for most systems. It provides enough space to build
LFS and most of BLFS, but is small enough so that multiple
partitions can be easily created for experimentation.
Most distributions automatically create a swap partition. Generally the recommended size of the swap partition is about twice the amount of physical RAM, however this is rarely needed. If disk space is limited, hold the swap partition to two gigabytes and monitor the amount of disk swapping.
Swapping is never good. Generally you can tell if a system is swapping by just listening to disk activity and observing how the system reacts to commands. The first reaction to swapping should be to check for an unreasonable command such as trying to edit a five gigabyte file. If swapping becomes a normal occurance, the best solution is to purchase more RAM for your system.
There are several other partitions that are not required, but should be considered when designing a disk layout. The following list is not comprehensive, but is meant as a guide.
/boot – Highly recommended. Use this partition to store kernels and other booting information. To minimize potential boot problems with larger disks, make this the first physical partition on your first disk drive. A partition size of 100 megabytes is quite adequate.
/home – Highly recommended. Share your home directory and user customization across multiple distributions or LFS builds. The size is generally fairly large and depends on available disk space.
/usr – A separate /usr partition is generally used if providing a server for a thin client or diskless workstation. It is normally not needed for LFS. A size of five gigabytes will handle most installations.
/opt – This directory is most useful for BLFS where multiple installations of large packages like Gnome or KDE can be installed without embedding the files in the /usr hierarchy. If used, five to ten gigabytes is generally adequate.
/tmp – A separate /tmp directory is rare, but useful if configuring a thin client. This partition, if used, will usually not need to exceed a couple of gigabytes.
/usr/src – This partition is very useful for providing a location to store BLFS source files and share them across LFS builds. It can also be used as a location for building BLFS packages. A reasonably large partition of 30-50 gigabytes allows plenty of room.
Any separate partition that you want automatically mounted upon
boot needs to be specified in the /etc/fstab. Details about how to specify
partitions will be discussed in Section 8.2,
“Creating the /etc/fstab File”.