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  • I have an 8.0 TB Drive which will soon start filling up with videos

  • I have two spare 4.0 TB Drives

  • The system is running Linux Mint 19 Tara and is my desktop system (Yes it's a big system able to support 6 HDD in total)

What's the best way to create redundancy with these three drives in case of Drive failure?

My thought's so far:

Option 1: Use only half the 8.0 GB drive and setup Raid 5 between three 4.0 TB volumes.

  • Pros: Simple and mature redundancy, may have performance benefits with striping.
  • Cons: Requires intervention to restore data access if any drive fails (I've not used Raid before and likely won't again until I need it so it would take me a day to refresh how to restore the array after a failed drive). Also it makes half of the 8.0 GB drive redundant.

Option 2: Combine the two 4.0 TB drives into one 8.0 TB Volume and Mirror the 8.0 TB Drive onto it.

  • Pros: Simple and transparent redundancy. Less chance that the active data will be on a Drive that fails. (If either of the two drives in the mirror fail I'll just replace it and recreate the mirror, if the 8.0 TB drive fails I will just buy another and restore from the mirror.)
  • Cons: Might not be possible to do without added layers of complexity?

My Primary Question is: Is Option 2 possible and if so how?

Your advice is also appreciated. :-)

Jesse the Wind Wanderer
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  • RAID 5 is not an option. When one drive fails, rebuilding the array takes a long time with drives this size. During that period, another failed drive means your data is lost. Also remember that RAID is not backup. – Tero Kilkanen Aug 05 '20 at 07:45

1 Answers1

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I think this is possible using LVM. You join the two 0.4TB disks into a RAID 0, then join this device with your 0.8TB disk using RAID 1. Another option is that you make a 0.8TB LV using 0.4TB disks, then join that LV and your 0.8TB disk in a RAID 1 configuration.

Farhad Kia
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  • That's a great solution. Can mdadm do that sort of double RAID on RAID setup? – Jesse the Wind Wanderer Aug 05 '20 at 13:30
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    Ah yes I see it can :-) [https://raid.wiki.kernel.org/index.php/A_guide_to_mdadm](https://raid.wiki.kernel.org/index.php/A_guide_to_mdadm) ***Raid 1+0 :** This is a raid 0, that is built up from raid-1 mirrors. As such, the individual raid elements can be grown or shrunk as above. There is also the inverted version, raid 0+1 which is a raid-1 mirror made from raid-0 arrays. Again the individual elements can be grown or shrunk as above.* – Jesse the Wind Wanderer Aug 05 '20 at 13:40
  • Thanks for the info :-) – Farhad Kia Aug 26 '20 at 06:03