I am struggling with setting up RAID5 for my workstation running Ubuntu. Having read a plenty of guides and tutorials I managed to:

  1. create a RAID5 array from 3 disks in Intel RST ROM Utility
  2. setup RAID array in Ubuntu using mdadm
  3. create ext4 filesystem on the dedicated volume and mount it

However, after rebooting everything just disappears (except BIOS setup), despite I have saved mdadm configuration (mdadm -E -s) into /etc/mdadm/mdadm.conf. I cannot see /dev/md/* devices, /proc/mdstat shows no arrays.

Am I doing something wrong? Maybe there is a secret how to make my RAID setup persistent?

Thanks in advance.

  • It will be useful if you can post the content of mdadm.conf and the output of sudo fdisk -l – biocyberman Mar 4 '16 at 12:09
  • And a second thought, Intel RST ROM Utility seems to be something for a Hardware RAID card you have. If that is true, you do not need to use mdadm. It's something for software RAID. – biocyberman Mar 4 '16 at 12:10
  • I also though that after setting up everything in BIOS, I do not need to configure software RAID, but the ROM utility is only a tool to assist mdadm: "There is an option ROM (OROM) component in the BIOS that can create Intel RST RAID volumes and serves as the interface to the Intel RST RAID volumes in the pre- boot environment. Before the BIOS passes control to the system bootloader, the OROM leaves a copy of the features it supports, such as RAID 5, in system memory. This data can be read by mdadm to determine what features can be used when creating an Intel RST volume." – Dmytro Prylipko Mar 4 '16 at 12:38

And the answer is: to build RAID on partitions (/dev/sdb1, /dev/sdc1 ...) rather than on entire devices.

  • I'm facing a similar issue with raid 10, and wanted to try your solution. How do you create partitions exactly? – liang Dec 19 '17 at 4:47

I suggest to check, try and retry with the following command:

mdadm --examine mdadm --assemble

Read more information from here and other places by googling: https://raid.wiki.kernel.org/index.php/RAID_Recovery

I faced a similar case and found out that my partition information was wrong and mdadm could not assemble.

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