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Currently I have three drives with 500GB, 1.5TB and 2TB and would like to know if it's possible with mdadm to build a RAID 1 on top of the 2TB drive and the other two pooled together.

Would this work if I first created a 2TB RAID with -level=linear and then a RAID 1 on top of it and the 2TB drive? I've not tried this before and would like to know if this setup would likely work or if there will be problems with performance or something else.

Edit: Can the people downvoting please leave a comment explaining why? The answer to this question does not seem obvious to me, so why all the downvotes?

jangxx
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    By philosophy and design votes are anonymous and **neither voting [up](http://serverfault.com/help/privileges/vote-up) nor voting [down](http://serverfault.com/help/privileges/vote-down) requires any mandatory explanation**. The tooltip that appears when your mouse pointer hoovers over the down button states: *"this question does not show any research effort; it is unclear or not useful"*. Also questions attract a down vote when not [well written](http://meta.serverfault.com/a/3609/37681), not quite [on-topic](http://serverfault.com/help/on-topic), missing details or an allround Bad Idea. – HBruijn Jul 29 '16 at 15:07
  • http://i.imgur.com/gEmn3z8.png – Tim Brigham Jul 29 '16 at 15:09
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    Well, if my research would have led to an answer I wouldn't have asked this question. – jangxx Jul 29 '16 at 15:10

1 Answers1

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Yes, that's possible. The linux block device layer allows for all kind of silly arrangements. You could LVM the two smaller disks and then combine that with the larger one to a RAID1 as just one option.

However, it's a stupid idea. This kind of setup is error prone, hard to maintain and understand and if things go sideways, it's far too easy to bury yourself even deeper because you somehow get lost in the complicated recovery procedures necessary.

Just buy another 2TB disk, create a RAID1 and have an easy setup.

Sven
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