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Chapter 5. Disk Partitioning
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## Chapter 5. Disk Partitioning

Fedora Core creates and uses several partitions on the available hard drives. You may customize both the partitions, and how the drives on your system are managed. Section 5.1, “General Information on Partitions” explains drive partitions in more detail.

| Configuring RAID Devices
RAID facilities enable a group, or array, of drives to act as a single device. Configure any RAID functions provided by the mainboard of your computer, or attached controller cards, before you begin the installation process. Each active RAID array appears as one drive within Fedora.

On systems with more than one hard drive you may configure Fedora Core to operate several of the drives as a Linux RAID array without requiring any additional hardware. Linux software RAID arrays are explained in Section 5.2, “Disk Druid”.

| Changing Your Mind
The installation process makes no changes to your system until package installation begins. You may use Back to return to previous screens and change your selections at any time.

Figure 5.1. Partitioning Options Screen

The box on the screen lists the available drives. By default, the installation process may affect all of the drives on your computer. To ensure that specific drives are not repartitioned, clear the check box next to those drives on this list.

The installation process erases any existing Linux partitions on the selected drives, and replaces them with the default set of partitions for Fedora Core. All other types of partitions remain unchanged. For example, partitions used by Microsoft Windows, and system recovery partitions created by the computer manufacturer, are both left intact. You may choose an alternative from the drop-down list:

Remove all partitions on selected drives and create default layout

  Avoid this option, unless you wish to erase all of the existing operating systems and data on the selected drives.

Use free space on selected drives and create default layout

  If the selected drives have capacity that has not been assigned to a partition, this option installs Fedora Core into the free space. This ensures that no existing partition is modified by the installation process.

Create custom layout

  You manually specify the partitioning on the selected drives. The next screen enables you to configure the drives and partitions for your computer. If you choose this option, Fedora Core creates no partitions by default.

Select Review and modify partitioning layout to customize the set of partitions that Fedora Core creates, to configure your system to use drives in RAID arrays, or to modify the boot options for your computer. If you choose one of the alternative partitioning options, this is automatically selected.

| Default Partitioning Scheme
The default partitioning scheme is sufficient for very simple uses, but it is not very flexible. It is also not easy for a new user to later reconfigure, as reconfiguring requires you to boot from another disk (such as the Fedora rescue disk). Even if you are a new user, if you think you may later want to do more sophisticated things, please consider setting the default layout, but selecting Review and modify partitioning layout, and allocating a smaller size to your system (it's easy to later extend this).

Choose a partitioning option, and select Next to proceed.

| The Next Screen
The next screen is Network Devices, explained Chapter 7, Network Configuration, unless you select an option to customize the partition layout. If you choose to either Create custom layout, or Review and modify partitioning layout, proceed to Section 5.1, “General Information on Partitions”.

## 5.1. General Information on Partitions

A Fedora Core system has at least three partitions:

- A data partition mounted at `/boot`

- A data partition mounted at `/`

- A swap partition

Many systems have more partitions than the minimum listed above. Choose partitions based on your particular system needs. If you are not sure how best to configure the partitions for your computer, accept the default partition layout.

Data partitions have a mount point. The mount point indicates the directory whose contents reside on that partition. A partition with no mount point is not accessible by users. Data not located on any other partition resides in the `/` (or root) partition.

| Root and `/root`
The `/` (or root) partition is the top of the directory structure. The `/root` (sometimes pronounced "slash-root") directory is the home directory of the user account for system administration.

In the minimum configuration shown above:

- All data under the `/boot/` directory resides on the `/boot` partition. For example, the file `/boot/grub/grub.conf` resides on the `/boot` partition.

- Any file outside of the `/boot` partition, such as `/etc/passwd`, resides on the `/` partition.

Subdirectories may be assigned to partitions as well. Some administrators create both `/usr` and `/usr/local` partitions. In that case, files under `/usr/local`, such as `/usr/local/bin/foo`, are on the `/usr/local` partition. Any other files in `/usr/`, such as `/usr/bin/foo`, are in the `/usr` partition.

If you create many partitions instead of one large `/` partition, upgrades become easier. Refer to the description of Disk Druid's Edit option for more information.

| Leave Excess Capacity Unallocated
Only assign storage capacity to partitions that you require immediately. You may allocate free space at any time, to meet needs as they arise.

### 5.1.1. Partition Types

Every partition has a partition type, to indicate the format of the file system on that partition. The file system enables Linux to organize, search, and retrieve files stored on that partition. Use the `ext3` file system for data partitions that are not part of LVM, unless you have specific needs that require another type of file system.

### 5.1.2. Understanding LVM

LVM (Logical Volume Management) partitions provide a number of advantages over standard partitions. LVM partitions are formatted as physical volumes. One or more physical volumes are combined to form a volume group. Each volume group's total storage is then divided into one or more logical volumes. The logical volumes function much like standard data partitions. They have a file system type, such as `ext3`, and a mount point.

An administrator may grow or shrink logical volumes without destroying data, unlike standard disk partitions. If the physical volumes in a volume group are on separate drives or RAID arrays then administrators may also spread a logical volume across the storage devices.

You may lose data if you shrink a logical volume to a smaller capacity than the data on the volume requires (though the Logical Volume Management tool tries to protect you from this). For this reason, create logical volumes to meet your current needs, and leave excess storage capacity unallocated. You may safely grow logical volumes to use unallocated space, as your needs dictate.

| LVM and the Default Partition Layout
By default, the installation process creates partitions within LVM volumes.

### 5.1.3. Creating a `/home` Volume

If you expect that you or other users will store data on the system, create a separate volume for the `/home` directory within your volume group. With a separate `/home` volume, you may upgrade or reinstall Fedora Core without erasing user data files. LVM provides you with the ability to add more storage capacity for the user data at a later time, without affecting the system volume.

### 5.1.4. New Users and LVM

If you are a new user, and you used the default layout but selected Review and modify partitioning layout, you will want to know what to do next. Use Disk Druid's Edit option to reduce the size of the single default logical volume that default layout gave you. Don't worry about leaving free space, you can easily claim it later, when you know what you want to do with it. Seriously consider, also, creating a separate /home volume - it's most likely that the space you will want to expand is /home, and changing the size of /home is easier if it's in a separate volume (of course, you will need to shrink the default logical volume first, to give you free space to create the /home volume).

How big should the volumes be? If you're a new user, it's unlikely you will want to set up disk-eating services like apache, so 10GB should be easily enough. If you have tons of disk space, and think you might want to later set up such services, 20GB should be ample. If you are leaving /home in the default volume, you will need to add its requirements to the size - for this, you need to estimate how much space you are likely to need. If you have set up a separate /home volume, its size should be large enough to contain your likely data, but it's easy to expand or shrink, so the accuracy of the estimate isn't so important. The size of the volume group also isn't too important - you might as well leave it occupying the whole disk space, it's easy to change later if you need to.

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