mdadm 3.3.2

A simple, smart and useful tool for creating, maintaining and monitoring Linux software RAID arrays

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What's new in mdadm 3.3:

  • This significant release included improved reshape support, improved DDF support, hot replace, and bad-block-log functionality.
  • Array names can now have names (md_home) instead of just numbers (md0).
  • There were several minor new features and many bugfixes.
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GPL (GNU General Public License) 
Neil Brown
2.7/5 26
ROOT \ System \ System Administration
1 mdadm Screenshot:
mdadm - Usage example of mdadm from the command-line
mdadm is an open source, small, fast and free command-line utility implemented in C and designed for maintaining, creating, and monitoring Linux "md" device arrays, popularly known as software RAID.

A minimal initramfs for assembling md arrays can be created using three files and one directory. These are the /bin directory, the /bin/mdadm statically linked mdadm binary, the /bin/busybox statically linked busybox binary, the /bin/sh hard link to /bin/busybox, and /init, a shell script which calls mdadm appropriately.

Command-line options

Default command-line options include the ability to create a new array from unused devices, assemble a previously created array, to create or assemble an array without metadata, to make changes to an existing array, to report on or modify several md related devices, to reshape or resize an active array, to remove or add a device from/to an array, as well as to monitor a single or multiple arrays.

Mandatory example

An example init script with an mdadm implementation would look like this:


echo 'Auto-assembling boot md array'
mkdir /proc
mount -t proc proc /proc
if [ -n "$rootuuid" ]
then arg=--uuid=$rootuuid
elif [ -n "$mdminor" ]
then arg=--super-minor=$mdminor
else arg=--super-minor=0
echo "Using $arg"
mdadm -Acpartitions $arg --auto=part /dev/mda
cd /
mount /dev/mda1 /root || mount /dev/mda /root
umount /proc
cd /root
exec chroot . /sbin/init < /dev/console > /dev/console 2>&1

Getting started with mdadm

To install and use the mdadm program in your GNU/Linux operating system, you should open the graphical package manager, search for mdadm and install the package. If mdadm is not available in the main software repositories of your distribution, download the latest version from Softpedia, where it is distributed as a source tarball.

Save the archive somewhere on your computer, extract its contents, open a terminal emulator and navigate to the location of the extracted archive files (e.g cd /home/softpedia/mdadm-3.3.2), where you must run the ‘make’ command to compile the program. Install it system wide by running the ‘sudo make install’ command.

mdadm was reviewed by , last updated on December 15th, 2014

#monitoring md device #creating md device #maintaining md device #RAID #monitor #maintain #administer

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