rebuilding RAID

RAID has never ever been a replacement for backups.

Without backups you will eventually lose data!
http://aplawrence.com/Linux/rebuildraid.html
Simple mdadm RAID 1 not activating spare
=======================
h20000.www2.hp.com/support/SupportManual/c00378986.pdf
support.dell.com/support/edocs/storage/RAID/SAS6iR/en/HTML/bio.htm
manuals.lacie.com/en/manuals/d2-2big-5big-network2/raid
forums.anandtech.com/showthread.php?t=300318
I have a fix for the AMD RaidXpert issue which does not require you to delete your Raid setup.
1) As posted, verify which drive is your data drive. It should be pretty easy because it will be the only drive in your raid view. Or follow the instructions above to find the drive you have your data on.
2) Reboot and go into your raid bios (-F) for my board but your's may differ.
3) Now I'm going from memory - should have written it down.
4) Go to Raid view I believe this is Number 1.
5) you should see your raid drive and your single drive
6) Define a new raid (don't remember which control sequence it is but, it's at the bottom of your screen)
7) Your single drive should appear as the only drive available.
8) In the options make the drive "raid ready"
9) Select it as assigned
10) Give it a name
11) Verify your settings
13) Don't initialize the drive
14) Reboot
15) In Windoze open the Raidxpert page.
16) Under Spare drives you will now have the "create" option available.
17) Click Create
18) Select the drive you marked as "raid-ready" (this should be the only drive)
19) Click Go
20) Your Raid 1 or Raid 5/10 should automatically see this drive as available and start rebuilding the drive system.
21) if not you can hit rebuild under the logical drive view once you select your raid drive.
The key is with a new system, the Raid Bios sees a new drive as a single drive which is not part of any raid system. This is kind of a safe guard, you don't want the system to take any drive you plug in as the new spare. So - as I said the key is to make your new drive "Raid-Ready" so that the raid system knows this drive is it's spare and can rebuild your Raid system.
This board gave me the right hint to go the "Raid-Ready" idea because I needed a spare drive not a single drive.
Using RAID 1 (Mirror) with the Onboard LSI MegaRAID SATA

[...] After the Operating System is installed: To check the status of the logical disk, you should use ServerView RAID and look at to see the initialization status (see picture below). ServerView RAID is installed by default if you install using the ServerStart media. To log into ServerView RAID use the Administrators username and password. If the status of the logical array is 'initialized', then all is well, but if, as above, it says "uninitialized", you need to run the MDC (Synchronization) process. By right clicking on the logical array you will see a menu pop up (as in the picture) which gives you the options of: Start initialization: DO NOT CLICK ON THIS. It will erase the contents of the logical disk. The option is only provided for the addition of a secondary array (not the primary O/S) Start MDC (Media Data Check): (For SAS and SATA) This is the correct tool for making the array consistent. Depending on the size of the disks, the MDC may take a long time. When the MDC is complete, the status of the array will change to being ‘initialized’ MDC is similar in functionality to the ‘check consistency’ setting associated with SCSI. Managing the replacement of a RAID disk. By default the adapter is set to do a automatic rebuild when a new disk is added. (The disk is marked for recovery as the OptionROM is initialized on boot) This is defined in the OptionROM (Ctrl-M) under [ Objects / Adapter / Auto Rebuild = enabled ] This can also be set in ServerView RAID. If automatic rebuild does not work, then also check that [Objects / Adapter / NewDevice = 'Auto Configuration']. If for some reason, one of the disks has gone off line and is still believed to be ok, then you can force a rebuild. You can do this in the OptionROM or ServerView RAID (recommended) DO NOT SELECT THE OPTION TO BRING THE DISK ONLINE.  This assumes that the data on both disks is still identical and the master disk has not been accessed since the failure occurred. Bringing the disk online may cause corruption which may not be immediately visible (for several months). The correct procedure is to use the REBUILD option.

https://forums.geforce.com/default/topic/356349/pc-components/nvraid-how-to-rebuild-degraded-arrays/1
Instructions for failure of Raid 1 (mirroring) 
First, you'll need to know which drive is on which SATA controller and mark them accordingly with a label on the drive. Note - The drive connected to Sata 0 is likely the bootable drive so if your operating system isn't booting up after a failure, simply reverse the drive positions, i.e. move the Sata 1 drive to the Sata 0 position (or swap cable positions on the motherboard). This should allow it to now boot into Windows. 
Once you've identified which drive goes to which Sata controller, test each drive by running the manufacturer drive test on them. (I have two WD drives mirrored and the mirror became corrupted and subsequent testing showed both drives good so not all corruptions are due to bad drives). If both drives are good, be sure to connect the drive labeled 0 to the SATA 0 connector and connect the other drive as well and go into the NVIDIA BIOS menu. Select each drive and look at it to see which is on controller 0 and which is on controller 1. Delete the drive on controller 1. Exit and save and boot into Windows and the NVRAID utility should automatically begin rebuilding the array. 
Note: If the mirror has been degraded for some time and much data has been written to it that is critical, it is important to isolate the drive that has the current information on it. To do this, hook up each drive to SATA 0 and boot to Windows (assuming each drive is not mechanically compromised) and check to see which drive has the current data on it. If the data is critical and the drive is failing mechanically, i.e. bad sectors, you'll need to look into data recovery. Which ever drive is most current would be connected to Sata 0 controller.
-----------------------------
I've got an ASUS A8N-VM-CMS Micro ATX motherboard with RAID 1 activated on 2 Maxtor SATA2 160Go hard disks drives.
After a brutal shutdown, my array goes degraded.
- Going into the Nvidia RAID bios utility by pressing F10 doesn't allow me to rebuild the array typing the R key do nothing (like you)
- Going under Windows and launching the Nvidia MediaShield utility doesn't allow me to rebuild the array ()
Then :
- Switch off the computer
- Open the computer
- Unplug the sata/ide cable from 1 of your 2 drives
- Reboot the computer
- Shutdown the computer and switch off
- Re-plug your sata/ide drive
- Press F10 on boot to go into the RAID bios utility and select R to rebuild, press F7 to confirm.
- Windows is now starting, and if you launch the Nvidia mediashield utility you will see that the rebuilding process is in progress.
PS : During this, i had to redefine the boot disk, bios config was lost, but don't know why.
--------------------------
I have the same problem but my circumstances are a bit different.
OS = Windows Small Business Server 2003.
HDD = Dual 200GB SATA Western Digital
DRIVES ARE ON SATA 1 AND SATA 2
RAID 1 MIRROR
OS resides on these drives.
To test the recovery from a degraded mirror, I unplugged SATA 2 from my setup while the computer was off to simulate drive failure during power outage. Computer is turned back on and the OS boots no problem. Once in Windows, Media Manager shows a degraded mirror - no problem. I powered down the computer, reconnected the drive, turn the computer back on. The raid is still degraged and Media Manager does not allow me to rebuild the array.
Your instructions are a bit vague and did not work for me. My solution was to enter the RAID setup (pressing F10 on startup), delete one of the drives from the array then add it back in by pressing F6. VOILA - raid mirror shows healthy again.
I am testing the fault tolerance of this NEW server so there is currently no data to lose. If you are doing this on an active system (server or not) then BACKUP YOUR DATA FIRST! I am able to risk all at this point since I am in testing mode.
Once back in Windows, Raid Manager shows raid is rebuilding. This process is slow so be patient. While the raid mirror was degraded, I created some new folders and made copies of some drivers that I had on the hard disk. It is now synchronizing the two drives.
I am going to repeat this a few times to ensure I have the process down correctly.
-----------------------------
I have a MSI K9N SLI board with a AMD 64 dualcore chip, onboard NVraid controler with Mediashield utility of jun 2006 running Vista 64 enterprice edition running with a mirror set on two SATA WDC WD2500 drives.
Using the system my set broke up showing a raid failer in a message box at the bottom of my screen and at next boot i got the message that new device drivers were being installed. When i tried to open my previous document I pannict because the total directory it was in was missing. Using search i foud it however on a D drive....which I should not have. But in 'My computer' I found that I suddenly had two drives... The C drive missed my wanted directory so I presume that C must have been the failing drive in the set.
Rebooting I also noticed in the Media shield utility the two drives...
Could also like You not rebuild etc...etc...
I followed your guide line and deleted my drive 0 as it must have ben my failing drive C then I could activate the rebuild command. had to hassle however in some sub commands to add a free drive in the set (my original deleted 0 drive) and got the statement on both drives that it got the status Rebuild.
I waited several hours concluded however that it was just sitting there doing nothing. I presumed that it might need the operating system to be alive and tried to boot.
Ahg.... got like one of you previuos mentiond into a bootmaster and looping every time i tried to boot telling me my drive was not bootable insert the installation disc etc..
I was able to boot from my instaltion disk on my CD/DVD and choose the repair option. I found a damaged boot block etc... and repaired it.
I rebooted my harddrives after that and was lucky...It came alive.
After that The harddrives came alive and were active for several hours in rebuilding them selfs.
My big concern in this case is however...It seems that for rebuilding a mirrorset the OS must be up...
What if my 0 drve was totaly damaged or replaced. should one make a new installation than? will it rebuild from a good mirror drive after that???