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I'm very new to RAID, so please bear with me.

I have 2 servers, both identical hardware, but one's running Windows Server 2003, the other is running CentOS.

I now need to make a clone of the Windows server on the machine that was running CentOS.

So, my question is... can I just shut down the running Windows Server, pull one of the HDs in the RAID array, replace it with one of the drives from the old CentOS machine, and put the HD from the Windows Server into the old CentOS machine?

What I'm hoping would happen is that I could rebuild the RAID array on the old CentOS machine from the Windows HD, and thus have my cloned machine.

Does this make sense? Would it work?

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Not enough detail to answer. It might work if you are using the right RAID form, and if..... etc. Please add some more information. –  Hennes Oct 19 '12 at 19:21
    
What type of hardware? Make/model? –  ewwhite Oct 19 '12 at 19:55

2 Answers 2

up vote 2 down vote accepted

I've done that before. It should work just fine as long as you have a RAID1. Before doing the above process:

  • delete the CentOS RAID set
  • boot the CentOS machine with ONLY the Windows HDD initially, import the RAID set, then re-add the CentOS drive for re-mirroring.
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As Hennes mentions, this is not always the case. It depends GREATLY on the type of RAID volume it is. –  Rex Oct 19 '12 at 19:35
    
Great info, thanks a lot. Just to clarify, would I do the same process on the original Win server... ie. delete the array, boot up into Windows, then re-add the RAID set? Or with that one am I fine to just put in the new drive? –  nathangiesbrecht Oct 19 '12 at 20:11
    
Nope, that'll make you lose all your data. –  MikeyB Oct 19 '12 at 20:23
    
Thanks guys, worked like a charm! –  nathangiesbrecht Oct 22 '12 at 14:34

If the disks are in stripe mode:
Forget swapping one disk at a time.
(Not that I see a sane reason for anyone to use stripe in a server, but for completeness sake.)


Assuming your disks are a mirror. (If you do not know what that is, read this post on this site It explains what the RAID levels are).

If it is hardware RAID:
You wrote both identical hardware, but double check if the RAID cards are of the same manufacturer. Most (all?) seem to put their RAID configuration on the drive. Which means you can swap one drive and insert another empty drive. Then rebuild/clone.

If they are not the same then it becomes a gamble. Same brand but never model will probably be fine. A different brand might be a challenge.

If it is fake software RAID
(IRSSI, Intel fake RAID etc.), then make sure the motherboards are the same. Again, you wrote that both identical hardware, but check. Different motherboards, chipsets and possibly BIOS/UEFI versions matter here.

I do not have much experience here, but general advise seems to stay far away from this. Either use plain software RAID, or use hardware RAID. I realise that this conflicts with your need to make a clone of the windows server, but if you are setting up a second server then now is a good idea to do it properly.

If it is normal software raid:
(LVM?) I never used this under windows. Best follow @MikeB's advise.


If the disks are in neither stripe nor mirror:
You will either need to use some form of backup- and restore-software. Or recreate one disk at a time by pulling a live drive out of the original server, and replacing it with a clean drive. Then do that for all bar one drive.

Note that I would not feel comfortable doing that. Esp. if the original server uses large disks in RAID5.


Regardless of what you do:

  1. Make sure you have an up to date backup.
  2. If I could repeat item 1 in blink tag, it would go here. Really.
  3. Actually test that backup.
  4. If you clone the server and it is not a domain controller read up on possible problems with unique identifiers in windows domain. (Which will not be unique if you clone a drive).
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