Appendix B. Partitioning reference

B.1. Supported device types

Standard partition
A standard partition can contain a file system or swap space. Standard partitions are most commonly used for /boot and the BIOS Boot and EFI System partitions. LVM logical volumes are recommended for most other uses.
Choosing LVM (or Logical Volume Management) as the device type creates an LVM logical volume. LVM can improve performance when using physical disks, and it allows for advanced setups such as using multiple physical disks for one mount point, and setting up software RAID for increased performance, reliability, or both.
LVM thin provisioning
Using thin provisioning, you can manage a storage pool of free space, known as a thin pool, which can be allocated to an arbitrary number of devices when needed by applications. You can dynamically expand the pool when needed for cost-effective allocation of storage space.

The installation program does not support overprovisioned LVM thin pools.

B.2. Supported file systems

This section describes the file systems available in Red Hat Enterprise Linux.

XFS is a highly scalable, high-performance file system that supports file systems up to 16 exabytes (approximately 16 million terabytes), files up to 8 exabytes (approximately 8 million terabytes), and directory structures containing tens of millions of entries. XFS also supports metadata journaling, which facilitates quicker crash recovery. The maximum supported size of a single XFS file system is 500 TB. XFS is the default and recommended file system on Red Hat Enterprise Linux. The XFS filesystem cannot be shrunk to get free space.
The ext4 file system is based on the ext3 file system and features a number of improvements. These include support for larger file systems and larger files, faster and more efficient allocation of disk space, no limit on the number of subdirectories within a directory, faster file system checking, and more robust journaling. The maximum supported size of a single ext4 file system is 50 TB.
The ext3 file system is based on the ext2 file system and has one main advantage - journaling. Using a journaling file system reduces the time spent recovering a file system after it terminates unexpectedly, as there is no need to check the file system for metadata consistency by running the fsck utility every time.
An ext2 file system supports standard Unix file types, including regular files, directories, or symbolic links. It provides the ability to assign long file names, up to 255 characters.
Swap partitions are used to support virtual memory. In other words, data is written to a swap partition when there is not enough RAM to store the data your system is processing.

The VFAT file system is a Linux file system that is compatible with Microsoft Windows long file names on the FAT file system.


Support for VFAT file system is not available for Linux system partitions. For example, /, /var, /usr and so on.

A very small partition required for booting from a device with a GUID partition table (GPT) on BIOS systems and UEFI systems in BIOS compatibility mode.
EFI System Partition
A small partition required for booting a device with a GUID partition table (GPT) on a UEFI system.
This small boot partition is located on the first partition of the disk. The PReP boot partition contains the GRUB2 boot loader, which allows other IBM Power Systems servers to boot Red Hat Enterprise Linux.

B.3. Supported RAID types

RAID stands for Redundant Array of Independent Disks, a technology which allows you to combine multiple physical disks into logical units. Some setups are designed to enhance performance at the cost of reliability, while others improve reliability at the cost of requiring more disks for the same amount of available space.

This section describes supported software RAID types which you can use with LVM and LVM Thin Provisioning to set up storage on the installed system.

Performance: Distributes data across multiple disks. RAID 0 offers increased performance over standard partitions and can be used to pool the storage of multiple disks into one large virtual device. Note that RAID 0 offers no redundancy and that the failure of one device in the array destroys data in the entire array. RAID 0 requires at least two disks.
Redundancy: Mirrors all data from one partition onto one or more other disks. Additional devices in the array provide increasing levels of redundancy. RAID 1 requires at least two disks.
Error checking: Distributes data across multiple disks and uses one disk in the array to store parity information which safeguards the array in case any disk in the array fails. As all parity information is stored on one disk, access to this disk creates a "bottleneck" in the array’s performance. RAID 4 requires at least three disks.
Distributed error checking: Distributes data and parity information across multiple disks. RAID 5 offers the performance advantages of distributing data across multiple disks, but does not share the performance bottleneck of RAID 4 as the parity information is also distributed through the array. RAID 5 requires at least three disks.
Redundant error checking: RAID 6 is similar to RAID 5, but instead of storing only one set of parity data, it stores two sets. RAID 6 requires at least four disks.
Performance and redundancy: RAID 10 is nested or hybrid RAID. It is constructed by distributing data over mirrored sets of disks. For example, a RAID 10 array constructed from four RAID partitions consists of two mirrored pairs of striped partitions. RAID 10 requires at least four disks.

B.5. Advice on partitions

There is no best way to partition every system; the optimal setup depends on how you plan to use the system being installed. However, the following tips may help you find the optimal layout for your needs:

  • Create partitions that have specific requirements first, for example, if a particular partition must be on a specific disk.
  • Consider encrypting any partitions and volumes which might contain sensitive data. Encryption prevents unauthorized people from accessing the data on the partitions, even if they have access to the physical storage device. In most cases, you should at least encrypt the /home partition, which contains user data.
  • In some cases, creating separate mount points for directories other than /, /boot and /home may be useful; for example, on a server running a MySQL database, having a separate mount point for /var/lib/mysql allows you to preserve the database during a re-installation without having to restore it from backup afterward. However, having unnecessary separate mount points will make storage administration more difficult.
  • Some special restrictions apply to certain directories with regards on which partitioning layouts can they be placed. Notably, the /boot directory must always be on a physical partition (not on an LVM volume).
  • If you are new to Linux, consider reviewing the Linux Filesystem Hierarchy Standard for information about various system directories and their contents.
  • Each kernel requires approximately: 60MiB (initrd 34MiB, 11MiB vmlinuz, and 5MiB
  • For rescue mode: 100MiB (initrd 76MiB, 11MiB vmlinuz, and 5MiB System map)
  • When kdump is enabled in system it will take approximately another 40MiB (another initrd with 33MiB)

    The default partition size of 1 GiB for /boot should suffice for most common use cases. However, it is recommended that you increase the size of this partition if you are planning on retaining multiple kernel releases or errata kernels.

  • The /var directory holds content for a number of applications, including the Apache web server, and is used by the DNF package manager to temporarily store downloaded package updates. Make sure that the partition or volume containing /var has at least 5 GiB.
  • The /usr directory holds the majority of software on a typical Red Hat Enterprise Linux installation. The partition or volume containing this directory should therefore be at least 5 GiB for minimal installations, and at least 10 GiB for installations with a graphical environment.
  • If /usr or /var is partitioned separately from the rest of the root volume, the boot process becomes much more complex because these directories contain boot-critical components. In some situations, such as when these directories are placed on an iSCSI drive or an FCoE location, the system may either be unable to boot, or it may hang with a Device is busy error when powering off or rebooting.

    This limitation only applies to /usr or /var, not to directories under them. For example, a separate partition for /var/www works without issues.


    Some security policies require the separation of /usr and /var, even though it makes administration more complex.

  • Consider leaving a portion of the space in an LVM volume group unallocated. This unallocated space gives you flexibility if your space requirements change but you do not wish to remove data from other volumes. You can also select the LVM Thin Provisioning device type for the partition to have the unused space handled automatically by the volume.
  • The size of an XFS file system cannot be reduced - if you need to make a partition or volume with this file system smaller, you must back up your data, destroy the file system, and create a new, smaller one in its place. Therefore, if you plan to alter your partitioning layout later, you should use the ext4 file system instead.
  • Use Logical Volume Management (LVM) if you anticipate expanding your storage by adding more disks or expanding virtual machine disks after the installation. With LVM, you can create physical volumes on the new drives, and then assign them to any volume group and logical volume as you see fit - for example, you can easily expand your system’s /home (or any other directory residing on a logical volume).
  • Creating a BIOS Boot partition or an EFI System Partition may be necessary, depending on your system’s firmware, boot drive size, and boot drive disk label. Note that you cannot create a BIOS Boot or EFI System Partition in graphical installation if your system does not require one - in that case, they are hidden from the menu.

B.6. Supported hardware storage

It is important to understand how storage technologies are configured and how support for them may have changed between major versions of Red Hat Enterprise Linux.

Hardware RAID

Any RAID functions provided by the mainboard of your computer, or attached controller cards, need to be configured before you begin the installation process. Each active RAID array appears as one drive within Red Hat Enterprise Linux.

Software RAID

On systems with more than one disk, you can use the Red Hat Enterprise Linux installation program to operate several of the drives as a Linux software RAID array. With a software RAID array, RAID functions are controlled by the operating system rather than the dedicated hardware.


When a pre-existing RAID array’s member devices are all unpartitioned disks/drives, the installation program treats the array as a disk and there is no method to remove the array.

USB Disks

You can connect and configure external USB storage after installation. Most devices are recognized by the kernel, but some devices may not be recognized. If it is not a requirement to configure these disks during installation, disconnect them to avoid potential problems.

NVDIMM devices

To use a Non-Volatile Dual In-line Memory Module (NVDIMM) device as storage, the following conditions must be satisfied:

  • The architecture of the system is Intel 64 or AMD64.
  • The device is configured to sector mode. Anaconda can reconfigure NVDIMM devices to this mode.
  • The device must be supported by the nd_pmem driver.

Booting from an NVDIMM device is possible under the following additional conditions:

  • The system uses UEFI.
  • The device must be supported by firmware available on the system, or by a UEFI driver. The UEFI driver may be loaded from an option ROM of the device itself.
  • The device must be made available under a namespace.

To take advantage of the high performance of NVDIMM devices during booting, place the /boot and /boot/efi directories on the device.


The Execute-in-place (XIP) feature of NVDIMM devices is not supported during booting and the kernel is loaded into conventional memory.

Considerations for Intel BIOS RAID Sets

Red Hat Enterprise Linux uses mdraid for installing on Intel BIOS RAID sets. These sets are automatically detected during the boot process and their device node paths can change across several booting processes. It is recommended that you replace device node paths (such as /dev/sda) with file system labels or device UUIDs. You can find the file system labels and device UUIDs using the blkid command.