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johnsitFlag for United Kingdom of Great Britain and Northern Ireland

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Mirroring data in Windows Server 2008 R2

Hi All,

This may sound like a simple question but maybe not so.

I am building a small media server with a HP Microserver, 1 system disk, 2 data disks.

The two disks will be used for data, the second being backup.

I initially thought of using the fake raid included (AMD raid) but went off the idea since should the server fail I would need another similar chipset to retrieve the data.

Then I investigated software raid (disk striping) in Server 2008R2 but again, if the server itself breaks I will not be able to break the mirror in order to read it on another PC.

I then thought about a robocopy script, run at shutdown but there are two issues with that,

The server shuts down before the script has completed, here I suppose I could script the copy, then script the shutdown but ideally I would like to just be able to press the power button, run the script then shut down. The reason for this is that I will not have a kvm plugged in and do not want to start another PC all the way up, just to run RDP to run the script each time I want to shut it down.

In a nutshell, Id like the server to sit on its own in a corner, be started and shut down with the power button and to hold a second copy of all the data on there.

Anyone any ideas how to perform this which should be a relatively simple task? I never thought it would be difficult :)

Thanks very much in advance.
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ASKER

Hi All,

Thanks for all the comments, very helpful!

Id like to stick to Windows as I plan to use some of the features (I also know it a lot better than Linux).

@andyalder: Sorry about that, I did of course mean mirroring (Raid 1), a bit of a typo there :)

To clarify, I don't want to mirror the OS, that is on a separate disk. The two disks I wish to mirror are the data.

From the posts I feel I definitely want to use Windows software mirror. I feel the bit I may be missing is the "Since it's only been converted to dynamc for mirroring you can even revert to basic with a simple hack of the partition table." stated by Andy as the disk shows as not initialized when I moved it to another PC so I think its this part I'm missing.....

Could you please tell me the safest way to perform this without data loss and preferably without third party tools?

Thanks again.
there are plenty of videos on youtube that walk you through this .. .but they are all the same.  You convert each disk to dynamic, then select the disk with the live data and the disk that you want to overwrite and let it run.

No big deal unless you get the disks backwards.
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ASKER

thanks for the comment, the issue is not creating the mirror, it is breaking the mirror when I want to retrieve the data on another server (for instance if the server itself breaks) that I am unsure how to do.
Don't do it.  If you want to break mirrors, create a 3-way mirror.   Reason is that if you break a two-way mirror then you have risk of data loss and corruption.

The software RAID does not do a verify on read on both disks.  So if disk A has a bad block at location 1234, but Disk B has a good block on 1234, and you break the mirror so that B is now the cloned copy ... then you mirror it back, disk B ends up with zeros in block #1234 and disk A ends up with an unrecovered read error.

(Forget the fact that disk A can even die in the middle of all of this).

Never, ever, break a perfectly good RAID1.  You have no way of knowing if either disk has an unrecoverable read error before you break the RAID, or develops one after the split.
If you want to retrieve data safely, then boot that other server to LINUX, and then it will mount the NTFS mirror as a read-only filesystem.  You can then read from it and copy it to the network or wherever safely.

Since the system won't be running Windows, then none of the files  can change so you can rest assured you'll get a clean copy.
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You should be able to import foreign disk on another system (assuming it knows about dynamic disks). There's no option for a 3-way mirror under Windows BTW.
You can mirror 3-ways in Win2008 by using the RAID controller as one mirror, and then using software mirroring to mirror the hardware-based mirror with the other drive.

Or use Win2K12 and ReFS...

If you do the mirror of the mirror then be aware you need to install the O/S on the mirrored hardware RAID first, and make that the boot. Then you won't run into a capacity issue since the capacity on the HP RAID will be less than the usable capacity on the stand-alone drive.

This is best of all worlds, when you swap out a drive to break the mirror, then you can use the HP disk as the swap in/out drive and the built in firmware will rebuild the mirror in the background.    It won't be as good as a true 3-way mirror, but you have added safety.  There are some rules that govern what can and can not be mirrored when you mix and match, so test this scenario. Pretty sure that you have to have all SAS internal disks or it won't work.
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ASKER

OK, thanks for all the comments guys n gals.

For some reason I retried the windows raid and it imported to a different computer fine. I think I may have made a mistake the first time I set the mirror up!

Thanks for all the comments, unless anyone has any objections I w3ill split the points with a little extra for AndyAlder for stressing that you should be able to import the mirror on other servers.

THANKS VERY MUCH TO ALL!