Restore redundancy in a software mirror

Josh Christie
Josh Christie used Ask the Experts™
on
We run Windows SBS 2003 on a Dell PowerEdge 840.  Yesterday we finished a maintenance task on the OS.  In the process we did some editing on one, ONLY ONE, of the HDDs that comprises part of a software mirror.  After plugging in the other HDD of the mirror, Disk Management shows Failed Redundancy.  We were hoping it would resync automatically the way a hardware mirror does.  But it did not.  How do I resync these drives?
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Commented:
Undo your mirror and then set it up again.

Author

Commented:
One of the disks has a warning icon on it.  I assume that is the one that is out of date.  If I right click on the disk, I can choose Reactivate Disk.  So I should NOT choose that?  Right click on the volume I could choose Reactivate Volume or Remove Mirror.  I think you're saying I should Remove Mirror.  Should I do it on the volume that has the warning?  Or on both?  Will I lose the data?
Commented:
On the warning volume - remove the mirror and then redo it.
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noxchoIT Product Manager
Top Expert 2009
Commented:
Take backup of system and data and only then reactivate the drive.
Also, instead of removing mirror - brake it. This will have less affect on first HDD or no affect.
Removing mirror removes volumes on both drives as far as I know. So do not use it. Brake mirror is correct operation here.

Commented:
This is a mirror - not a stripe

Author

Commented:
Break Mirrored Volume is grayed out.

Author

Commented:
So really, the mirror is already broken.  Is it possible to restore the mirror without formatting and hence losing all the data?  Will Reactivate Disk do that?  

Commented:
That will happen automatically
noxchoIT Product Manager
Top Expert 2009

Commented:
Can you take a screen shot of your Windows Disk Management and post it here? That would give us more space for manoeuvring with our advice.

Author

Commented:
Can I Reactivate the Disk drive while the drive is in use?
Commented:
Yes

Author

Commented:
How smart is it?  Do the most recent edits get preference?  Or does the disk with the most recent edits dominate the other disk?

Commented:
Break the mirror and choose the proper HD when you re-establish the new mirror.
noxchoIT Product Manager
Top Expert 2009

Commented:
I think screenshot would give us more info.

Author

Commented:
Here is a screen shot.  

As you can see, there is another issue here I have not yet mentioned.  This is where we converted the main Disk from Dynamic to Basic.  The new Basic disk is healthy and functioning great.  But the remnants of the old dynamic are still there.  I suppose I can delete that.  But that's a separate issue.
Document.doc
noxchoIT Product Manager
Top Expert 2009
Commented:
Yes, you can delete the remnants.
As for H: drive, when you click on volume of disk 3 - do you get Brake Mirror option?

Author

Commented:
No.  The options are identical for both Disk 2 and Disk 3.   The options NOT available for both are Break Mirrored Volume, and Repair Volume.
noxchoIT Product Manager
Top Expert 2009

Commented:
Ok, do you have data on H: drive and if yes are you able to get to that data via Windows Explorer?

Author

Commented:
Yes, I have data on the H: drive and I can get to that data in Windows Explorer.  We are using that data constantly.  However, I assume that we are using one of the physical drives and not the other at the moment.  That one of them is updating normally and the other one is dormant... probably.  Maybe the only way to tell for sure is to disconnect them one at time and see what I get then.
IT Product Manager
Top Expert 2009
Commented:
If you have access to data please copy it to another non mirror drive. Then delete the mirror. When both HDDs are detected as ok with no triangle warning marks on them copy the data back and rebuild the mirror. This precaution step is needed as you do not know exactly which HDD is used at the moment.
So copy - remove - rebuild - copy back would be most correct here.

Author

Commented:
I expect to try it tonight
noxchoIT Product Manager
Top Expert 2009

Commented:
Ok. Good luck.

Author

Commented:
Well, I didn't get to it last night... plan to try tonight now.
noxchoIT Product Manager
Top Expert 2009

Commented:
Really no hurry. I think we can keep this thread open till you decide to close it.

Author

Commented:
We have success.  I found this site...
http://technet.microsoft.com/en-us/library/cc786839(WS.10).aspx
... which encouraged me to try Reactivate Disk first, and then if that failed to give me the latest version of the files, then to opt for the more conservative... Format, Rebuild... method.  
So I chose Reativate Disk.  Immediately the two HDDs went into resync mode and after a couple of hours became Healthy.  Spot checking seems to indicate that we have the latest version of the files.

So thank God and thank you.

Author

Commented:
The solution was good, but I ended up using an easier alternative that maybe had the potential for being less foolproof, but seems to have worked.  

Commented:
Nobody listens to me ;)

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