15-A.1: Linux Installation
- Page ID
- 43519
Objectives of this Module
In this lesson, you will:
- Learn the steps to prepare for installing the Linux operating system.
- Perform the actual installation of Linux.
First Things
Even though Linux is a single operating system, the various distributions have slight variations that a user needs to consider when determining which distro to add to their data center. Most of the distributions have a page on their web site that lists the hardware requirements for all active versions. It is a necessity to take the time and verify that the potential hardware platform is compatible with the potential distribution of Linux.
As the popularity of Linux grows, it is more and more likely that that each distribution will support a wider range of hardware, but still, it is a good idea to verify all the pieces. For instance, CentOS has a list of specifications for the currently supported CentOS versions.
Notice that the newer version, CentOS 8, does NOT support the older i386 processors. The supported memory is also different for the newer versions. All of these are things that need to be verified before a decision is made about the distribution and the version.
Most Linux distributions have pages like this on their web sites - use them to verify your needs.
Partition: How Should it Look?
Disk partitioning or disk slicing is the creation of one or more regions on secondary storage, so that each region can be managed separately.
An entire disk may be allocated to a single partition, or multiple ones may be allocated for cases such as dual-booting, maintaining a swap partition, or to logically separate data such as audio and video files. The partitioning scheme is stored in a partition table such as Master Boot Record (MBR) or GUID Partition Table (GPT).
Partition tables are created and modified using one of many partitioning tools. The tools available for Arch Linux are listed in the #Partitioning tools section.
Partitions usually contain a file system directly which is accomplished by creating a file system on (a.k.a. formatting) the partition. Alternatively, partitions can contain LVM, block device encryption or RAID, which ultimately provide device files on which a file system can be placed (or the devices can be stacked further).
Any block device (e.g., disk, partition, LUKS device, LVM logical volume or RAID array) that directly contains a mountable file system is called a volume.
Disk partitioning in the past was much more critical. The disk drives were not that big, and as an administrator there was a desire to use the disk space as efficiently as possible. A great deal of planning went into what partitions were going to be created, and how much space to allocate to each partition.
With the larger drives now, there is less concern about squeezing every last usable bit out of the partitioning scheme. However, as an administrator, you should still be aware of the efficient partitioning of the disk drives.
Depending on the distribution the size may be different. The following is a sample from Fedora Linux.
- /boot - 500 MB
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This partition contains the operating system kernel, which allows Fedora to boot. It also contains other files used during the bootstrap process. Due to the limitations of most firmware, creating a separate, small standard partition for this directory is recommended. In most scenarios, a 500 MB /boot partition is adequate.
- / (root) - 10 GB
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This is where the root directory is located. The root directory is the top level of the directory structure. By default, all files are written to this partition unless a different partition is mounted in the path being written to (for example, /boot or /home ). If you follow the recommended scheme described in this section, this will be the partition where most software packages will be installed.
For a minimal installation, a 5 GB root partition will be sufficient. However, for most common installations which include extra packages and a graphical user interface, the root partition should be at least 10 GB; with 20 GB being sufficient for most common use cases.
- /home - at least 10 GB
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To store user data separately from system data, create a dedicated mount point for the /home directory. This partition should be sized based on the amount of data that will be stored locally, number of users, and so on. This will allow you to upgrade or reinstall Fedora without erasing user data files. During the installation, a separate /home partition will be created if there are 50 GB or more of free space for your Fedora installation.
When using Fedora as a workstation for normal use with a graphical environment, this mount point should have the most disk space assigned to it, as it will likely hold the most data (user settings, images, videos, etc).
Other partitions are allowed. In some scenarios you might want to put /usr and /var in their own partitions as well. In the above example - where / is 10 GB, that is because it includes /usr and /var, which are both full of executable files, libraries, and log files, all of which take up a tremendous amount of space.
One example system where this is done you can see: /, /usr, /home and /var are all on different partitions. As the system administrator you decide how to divide up the disk space.
/dev/sda1 8940016 5706604 2756228 68% /
/dev/sda2 80503616 11995828 64395404 16% /usr
/dev/sda6 310238080 127966488 166489348 44% /home
/dev/sda5 80503616 24267152 52124080 32% /var
SWAP Partition
Swap partitions support virtual memory; data is written to them when there is not enough RAM to store the data your system is processing. This partition's size is a function of system memory workload, not total system memory, and therefore is not equal to the total system memory size. Therefore, it is important to analyze what applications a system will be running and the load those applications will serve in order to determine the system memory workload. Application providers and developers should be able to provide some guidance.
When the system runs out of swap space, the kernel terminates processes as the system RAM memory is exhausted. Configuring too much swap space results in storage devices being allocated but idle, and is a poor use of resources. Too much swap space can also hide memory leaks. The maximum size for a swap partition and other additional information can be found in the mkswap(8) man page.
The table below provides the recommended size of a swap partition depending on the amount of RAM in your system and whether you want sufficient memory for your system to hibernate. If you let the installation program partition your system automatically, the swap partition size will be established using these guidelines. Automatic partitioning setup assumes hibernation is not in use, and the maximum size of the swap partition is limited to 10% of the total size of the hard drive. If you want to set up enough swap space to allow for hibernation, or if you want to set the swap partition size to more than 10% of the system's storage space, you must edit the partitioning layout manually.
| Amount of RAM in the system | Recommended swap space | Recommended swap space if allowing for hibernation |
|---|---|---|
| less than 2 GB | 2 times the amount of RAM | 3 times the amount of RAM |
| 2 GB - 8 GB | Equal to the amount of RAM | 2 times the amount of RAM |
| 8 GB - 64 GB | 0.5 times the amount of RAM | 1.5 times the amount of RAM |
| more than 64 GB | workload dependent | hibernation not recommended |
At the border between each range listed above (for example, a system with 2 GB, 8 GB, or 64 GB of system RAM), discretion can be exercised with regard to chosen swap space and hibernation support. If your system resources allow for it, increasing the swap space may lead to better performance.
Adapted from:
"CentOS Product Specifications" by Christoph Galuschka is in the Public Domain, CC0
"5.4.10.6. Recommended Partitioning Scheme" by Multiple Contributors, Fedora Documentation is licensed under CC BY-SA 3.0