Manual Partitioning

An installation of CentOS requires a PReP boot partition and one other partition but CentOS recommends at least five: PReP, /, /home, /boot, and swap. You can also create additional partitions you require. See Recommended Partitioning Scheme (ppc) for further details.

Adding a file system is a two-step process. You first create a mount point in a certain partitioning scheme. The mount point appears in the left pane. Next, you can customize it using the options in the right pane, where you can change the mount point, capacity, the device type, file system type, label, and whether to encrypt or reformat the corresponding partition.

If you have no existing file systems and want the installation program to create the required file systems and their mount points for you, select your preferred partitioning scheme from the drop-down menu in the left pane (default for CentOS is LVM), then click the link on top of the pane for creating mount points automatically. This will generate a /boot partition, a / (root) volume, and a swap volume proportionate to the size of the available storage. These are the recommended file systems for a typical installation, but you can add additional file systems and mount points if you need to.

Alternatively, create individual mount points using the + button at the bottom of the pane. The Add a New Mount Point dialog then opens. Either select one of the preset paths from the Mount Point drop-down menu or type your own; for example, select / for the root partition or /boot for the boot partition. Then enter the size of the file system in the Desired Capacity text field; for example, 2GiB. If you leave the field empty or if you specify a size bigger than available space, all remaining free space is used instead. After entering these details, click the Add mount point button to create the partition.

For each new mount point you create manually, you can set its partitioning scheme from the drop-down menu located in the left pane. The available options are Standard Partition, BTRFS, LVM, and LVM Thin Provisioning. Note that the /boot partition will always be located on a standard partition, regardless of the value selected in this menu.

To change on which devices a single non-LVM mount point should be located, select the mount point and click the Modify…​ button in the right pane to open the Configure Mount Point dialog. Select one or more devices and click Select. After the dialog closes, note that you also need to confirm this setting by clicking the Update Settings button on the right side of the Manual Partitioning screen.

To refresh information about all local disks and partitions on them, click the Rescan button (with the circular arrow icon on it) in the toolbar. You only need to do this action after performing advanced partition configuration outside the installation program. Note that if you click the Rescan Disks button, all configuration changes you previously made in the installation program will be lost.

At the bottom of the screen, a link states how many storage devices have been selected in Installation Destination (see Installation Destination (ppc)). Clicking on this link opens the Selected Disks dialog, where you review the information about the disks. See Boot Loader Installation (ppc) for more information.

To customize a partition or a volume, select its mount point in the left pane and the following customizable features then appear to the right:

See File System Types (ppc) for more information about file system and device types.

Click the Update Settings button to save your changes and select another partition to customize. Note that the changes will not be applied until you actually start the installation from the Installation summary page. Click the Reset All button to discard all changes to all partitions and start over.

When all file systems and mount points have been created and customized, click the Done button. If you chose to encrypt any file system, you will now be prompted to create a passphrase. Then, a dialog appears, showing a summary of all actions related to storage that the installation program will take. This includes creating, resizing, or deleting partitions and file systems. You can review all the changes and click Cancel & Return to Custom Partitioning to go back. To confirm your changes, click Accept Changes to return to the Installation Summary page. To partition additional devices, select them in the Installation Destination screen, return to the Manual Partitioning screen, repeat the steps outlined in this section for the additional devices.

Logical Volume Management (LVM) presents a simple logical view of underlying physical storage space, such as hard drives or LUNs. Partitions on physical storage are represented as physical volumes that can be grouped together into volume groups. Each volume group can be divided into multiple logical volumes, each of which is analogous to a standard disk partition. Therefore, LVM logical volumes function as partitions that can span multiple physical disks.

To learn more about LVM, see Understanding LVM or read the Red Hat Enterprise Linux 7 Logical Volume Manager Administration guide. Note that LVM configuration is only available in the graphical installation program.

To create a logical volume and add it to a new or existing volume group:

Unless you have a reason for doing otherwise, CentOS recommends that you create the following partitions: