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I was wondering if it is possible to setup a hardware RAID 1 array on 2x1TB drives for the installation of Ubuntu 12.04 whilst leaving some space free outside of the RAID array to install Windows XP on? Am I completely wrong in thinking this could be possible or even a viable way of doing things? The Windows XP part would just be used to play a few games very rarely, whereas the Ubuntu side would contain all of the important stuff. If this is possible and a good idea, can someone recommend a way of setting this up? I've never implemented a RAID before.

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Yes, it is possible but IMHO it is not the best solution. What type of RAID controller you will use - Intel Matrix on-board one (aka "fake RAID"), Ubuntu software RAID (via md) or you have dedicated controller? – grs Jan 4 '13 at 21:03
I was going to use RAID on the motherboard (MSI 990XA-GD55). I recently had a hard drive fail without warning and lost everything, which I would like to try to minimise this time, which is why I am considering RAID 1... – Mark Aroni Jan 4 '13 at 21:15

If it is a hardware RAID, the device will be detected as a single disk by the OS.

Maybe what you intend is to create volume groups on top of logical volumes. That will allow more flexibility in order to have part of the physical volumes working as RAID 1 while other part of the devices can be used just in plain mode (no RAID).

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Taking into account that your Windows XP partition will be used occasionally only for games it may be worth considering a non-standard approach:

  1. Setup RAID1 in Ubuntu but use the drives only partially. For instance, instead of 2x1TB use 2x900GB. This will leave ballpark 100GB per drive for Windows XP;
  2. As it is dual-boot system, you can setup RAID0 for 2x100GB left from the RAID1 config. They never will be used at the same time. This will give you some performance improvement for your Windows, while protecting your Linux data.

With this config for sure you will be notified if a drive is failing. Then during Windows installation choose one of the small partitions. I believe you can get software RAID0 in Windows for the 2x100GB.

The disadvantage is that your on-board RAID won't be used, but at least you will be notified for drive troubles. Same for Windows.

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This sounds like a good idea. The computer is fast so software RAID wouldn't be a problem and may be easier for me to setup, although I probably would prefer it was handled by the hardware. So would this approach not use hardware RAID at all? – Mark Aroni Jan 4 '13 at 22:31
I can set this up as you have said in hardware, why did you say the disadvantage would be that the ob-board RAID wouldn't be used? – Mark Aroni Jan 4 '13 at 22:43
Because I was not sure if the on-board controller would be able to use drives partially, i.e. 2x900GB in RAID1 and 2x100GB in RAID0. I thought it can just get the whole drive. If you choose to go with the MB controller, just make sure it will let you know about drive failure. – grs Jan 4 '13 at 23:03
How would I find out if it will let me know about drive failure? – Mark Aroni Jan 4 '13 at 23:16
Create RAID, unplug the cable from one of the drives and see what happens :) – grs Jan 5 '13 at 1:51

I see three options:

  1. Use a HW RAID card. From your comment I understand I can skip this. Most would not support using part of a disk anyway, which would leave you with a single RAID mirror on which you could install Linus (as desired) and windows (also forced into the same mirror).
  2. Use Intel Fake RAID. This is software RAID which needs drivers loaded, which used to be (or still is?) suboptimally supported in Linux and which has a problem if the motherboard dies. You would need a similar motherboard to re-recognise the setup. Moving the risk from drive failure to MB failure.
  3. Use software RAID.

Software RAID can be used on part of the drives. For Linux you want to look at mdadm.

Assuming two 1TiB drives you could then do something like this:

1TiB drive 1:   0MB-900MB part of linux mirror -- 900MB - 1000MB free for windows
1TiB drive 2:   0MB-900MB part of linux mirror -- 900MB - 1000MB free for windows

You would use something like this to create the mirror:
mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1

That would put all the Linux stuff in a mirror called md0 and you would install Linux to that md0.

The remaining space (sda2 and sdb2) could be used to install windows. E.g. as two simple volumes, one containing the OS, one containing the data you use under windows.

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I don't have a separate hardware controller card, just that on the motherboard. The motherboard does seem to support doing this. – Mark Aroni Jan 4 '13 at 22:45

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