RHEL8 File systems

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  • LUKS stands for Linux Unified Key Setup.
  • This is the standard way to encrypt disks on Linux.

New version

  • The LUKS version 2 (LUKS2) format replaces the legacy LUKS (LUKS1) format.
  • The dm-crypt subsystem and the cryptsetup tool now uses LUKS2 as the default format for encrypted volumes.
  • LUKS2 provides many improvements and features, for example, it extends the capabilities of the on-disk format and provides flexible ways of storing metadata.


  • The RHEL 8 installer now supports the LUKS2 disk encryption format.
  • It uses this format by default but you can select a LUKS version from Anaconda’s Custom Partitioning window or by using the new options in Kickstart’s autopart, logvol, part, and RAID commands.



  • XFS is the default file system since RHEL 7.

Support for shared copy-on-write data extents

  • This feature enables two or more files to share a common set of data blocks.
  • It is fast: creating shared copies does not utilize disk I/O.
  • It is space-efficient: shared blocks do not consume additional disk space.
  • It is transparent: files sharing common blocks act like regular files.
  • This allows efficient file cloning and per-file snapshots.
  • This feature is enabled by default when creating an XFS filesystem.
  • RHEL 7 servers can mount XFS file systems with shared copy-on-write data extends only in read-only mode.
  • To create an XFS file system without this feature:
    • # mkfs.xfs -m reflink=0 block-device

Increase of maximum XFS file system size

  • The maximum supported size of an XFS file system has been increased from 500 TiB to 1024 TiB.


ext4 file system now supports metadata checksum

  • This enables the file system to recognize the corrupt metadata, which avoids damage and increases the file system resilience.


Installing and booting from NVDIMM devices is now supported

  • Kernel improvements to support NVDIMM devices provide improved system performance capabilities and enhanced file system access for write-intensive applications like database or analytic workloads, as well as reduced CPU overhead.
  • New nvdimm Kickstart command allows unattended installation.


The BOOM boot manager simplifies the process of creating boot entries

  • BOOM is a boot manager for Linux systems that use boot loaders supporting the BootLoader Specification for boot entry configuration. It enables flexible boot configuration and simplifies the creation of new or modified boot entries: for example, to boot snapshot images of the system created using LVM.
  • BOOM does not modify the existing boot loader configuration, and only inserts additional entries. The existing configuration is maintained, and any distribution integration, such as kernel installation and update scripts, continue to function as before.
  • BOOM has a simplified command-line interface (CLI) and API that ease the task of creating boot entries.
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RHCSA7: Task of the day

Allowed time: 5 minutes.
Configure a cron task to write the uptime at 2PM every day.

RHCE7: Task of the day

Allowed time: 10 minutes.
Configure a system to forward all email to a central mail server at (change the IP address accordingly).

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