I'm running Ubuntu 14.04 on a system with three hard disks in a RAID 0 configuration. The setup of the RAID was essentially this:

mdadm --create --verbose /dev/md0 --level=0 --raid-devices=3 /dev/sdb1 /dev/sdc1 /dev/sdd1
mdadm --detail --scan >> /etc/mdadm/mdadm.conf
update-initramfs -u

Then I created a partition on /dev/md0 and added it to /etc/fstab using its UUID that I got from blkid. Everything seems to work, also after rebooting.

However, I've read somewhere that using the UUID of a RAID partition in /etc/fstab is potentially dangerous because the RAID driver might not be available at the point when fstab is processed or something like that, so that this UUID would not mean anything.

I'm not a linux expert unfortunately. My question is therefore whether using the UUID of a RAID partition in /etc/fstab is safe or whether it could potentially cause problems? If the latter is the case, what would be the best alternative?


It shouldn't be a problem. If fstab contains an entry that points to an unavailable disk, it will simply be ignored. That's only a problem should that partition be your boot partition, the system will be unbootable. For any other partition, it simply won't be mounted. I think that systemd even tries for a while instead of just giving up.

Do note you need to use the UUID of the filesystem. You can find this by running blkid on the partition that contains the filesystem.

Software RAID is fully integrated in the kernel, so really, it should be available. My personal configuration is basically software RAID1 + LVM on top, so one layer of abstraction more.

One, slightly offtopic, question: A RAID0 on three disks? Why?!?

  • 1
    Thanks a lot! We use this to store input data and intermediate results from scientific computations. That requires lots of storage space and decent performance characteristics, but we don't care about data redundancy since this is only temporary storage. – Niko Aug 25 '16 at 12:49

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