Installing Open CAS Linux

This section describes how to perform a typical installation of Open CAS Linux. The installation package consists of loadable kernel modules that provide the caching layer and a management CLI that controls caching behavior.

Disabling Sleep States

Before configuring Open CAS Linux, you must disable Power Management Suspend (S3) and Hibernate (S4) states on your OS. Consult your OS documentation for how to accomplish this on your particular OS.

Configuring the Flash Device

Before configuring Open CAS Linux, you must have a flash device installed. The flash device can be any solid state drive (SSD) or any PCIe* flash drive supported by the Linux operating system (see System Requirements for details).

Follow the instructions in the installation guide included with the flash device, and make note of the device’s serial number or WWN so you can identify it once the system is up and running. All devices to be used for Open CAS Linux should be un-mounted and any auto-mount procedures disabled. When using a partition of a device as cache space, make sure the partition is aligned to the device’s physical sector size for best performance.

For best performance, it is recommended to use the noop (or None for NVMe devices) IO scheduler on the cache device (SSD). Initially, the cas virtual block device that is created when caching is enabled will inherit the IO scheduler of the primary storage device. If desired, the user can change the IO schedulers of the virtual block device and primary storage device independently after the virtual block device is created.

NOTE: Mounting file systems by label, such as in /etc/fstab, should not be used in older SysV based operating systems (RHEL 6.x, CentOS 6.x, etc) because it interferes with proper startup of Open CAS Linux. This is due to the file system already being mounted by the operating system when Open CAS Linux tries to start.

Code compilation

Before you begin installation, log on as an administrator or verify that you have the requisite privileges to install software. You must have “root” privileges or login as “root” in order to proceed.

  1. Download or clone the Open CAS Linux source files to a directory on the target system. The installation instructions use the example of ~ or ~/ (equivalent of $HOME) on the server file system. Optionally, Open CAS Linux can be cloned with:

    git clone

  2. Change current directory to project folder and update submodules

    cd open-cas-linux
    git submodule update --init

  3. Configure Open CAS Linux


  4. Compile Open CAS Linux and install it

    make install

  5. The main outputs of the compilation will be :
    • cas_disk.ko - CAS Disk Kernel Module
    • cas_cache.ko - CAS Cache Kernel module
    • casadm - CAS Administration Tool Note that the kernel modules will be inserted during the installation phase
  6. Verify casadm shows the inserted kernel module versions

    casadm -V

Creating RPM/DEB packages

You can generate RPM/DEB packages from Open CAS Linux sources and install them, instead of compiling the code and installing files manually. That is also an easy way to manage kernel modules updates from one kernel version to another. To generate packages, simply run:
make rpm or make deb (package generating script will inform you of any missing dependencies or other problems)

Your packages will be placed in packages/ directory. There will be two main ones (with utils and modules) and also debug symbols. You can ignore and delete all those containing debug or dbg in the file name.

Install open-cas-linux and open-cas-linux-modules by running:
dnf install ./packages/open-cas-linux*.rpm or apt install ./packages/open-cas-linux*.deb

To install common dependencies for building RPM packages:
dnf install rpm-build

To install common dependencies for building DEB packages:
apt install debhelper devscripts dkms