--- title: "Configuring a Software Mirror (RAID) on Windows" description: "Learn how to reconfigure the disk mirror of your Windows system if it needs to be rebuilt due to corruption or disk failure." url: https://docs.us.ovhcloud.com/en/bare-metal-cloud/dedicated-servers/configuring-software-mirror-raid-windows lang: en --- > For AI agents: the complete documentation index is available at https://docs.us.ovhcloud.com/en/llms.txt, the full documentation bundle is available at https://docs.us.ovhcloud.com/en/llms-full.txt. # Configuring a Software Mirror (RAID) on Windows **Learn how to reconfigure the disk mirror of your Windows system if it needs to be rebuilt due to corruption or disk failure.** On a Windows system, data redundancy is achieved by mirroring the primary disk to a second one. This is similar to a RAID 1 configuration but only involves two disks. ## Requirements - A Windows [dedicated server](https://us.ovhcloud.com/bare-metal/) with a software mirror - Administrative access to the server via RDP ## Instructions Establish a remote desktop (RDP) connection to your server. Once logged in, right-click on the `Start Menu` button and open `Run`.   Enter "cmd" and click on `OK`. The method to use depends on the partition style of your disks. Follow the instructions below for **MBR** or skip to the [subsequent section](#GPT) for **GPT**. If you are unsure, run `diskpart` at the command prompt and enter `list disk`. Check the "Gpt" column in the output.   ### Rebuilding the mirror (MBR partition scheme) At the command prompt, open DiskPart: ``` C:\Windows\system32> diskpart ``` **Important:** **WARNING:** DiskPart executes commands without issuing warnings or asking for confirmation. Any changes done in DiskPart are irreversible. Entering commands while the wrong disk or volume is selected may therefore cause immediate data loss and/or prevent your system from booting. We recommend to proceed with caution and double-check each command. #### #### Listing all disks and volumes ``` DISKPART> list disk Disk ### Status Size Free Dyn Gpt -------- ------------- ------- ------- --- --- Disk 0 Online 447 GB 0 B * Disk 1 Online 447 GB 447 GB Disk M0 Missing 0 B 0 B * DISKPART> list volume Volume ### Ltr Label Fs Type Size Status Info ---------- --- ----------- ----- ---------- ------- --------- -------- Volume 0 C Windows NTFS Mirror 447 GB Failed Rd System ``` In this example, `Disk 1` is a replacement drive that has been installed to replace the defective `Disk M0` which had been physically removed previously. **Note:** The following code sections are for illustration only, based on the example output above. You will need to adjust the instructions according to your actual configuration by replacing the values in the commands with your disk and volume identifiers. #### #### Removing the replaced disk from the configuration ``` DISKPART> select volume c Volume 0 is the selected volume. DISKPART> break disk M0 nokeep DiskPart successfully broke the mirror volume. DISKPART> list volume Volume ### Ltr Label Fs Type Size Status Info ---------- --- ----------- ----- ---------- ------- --------- -------- Volume 0 C Windows NTFS Simple 447 GB Healthy System DISKPART> select disk m0 Disk M0 is now the selected disk. DISKPART> delete disk DiskPart successfully deleted the missing disk. DISKPART> list disk Disk ### Status Size Free Dyn Gpt -------- ------------- ------- ------- --- ---s Disk 0 Online 447 GB 0 B * Disk 1 Online 447 GB 447 GB ``` #### #### Initializing the replacement disk ``` DISKPART> select disk 1 Disk 1 is now the selected disk. DISKPART> convert mbr DiskPart successfully converted the selected disk to MBR format. DISKPART> convert dynamic DiskPart successfully converted the selected disk to dynamic format. ``` #### Recreating the mirror between the first and the second disk ``` DISKPART> select volume c Volume 0 is the selected volume. DISKPART> add disk 1 DiskPart succeeded in adding a mirror to the volume. <===> DISKPART> list disk Disk ### Status Size Free Dyn Gpt -------- ------------- ------- ------- --- --- * Disk 0 Online 447 GB 0 B * Disk 1 Online 447 GB 0 B * ``` Repeat this step for each existing volume from `Disk 0` that you want to mirror on `Disk 1`, using the associated drive letter (i.e. _d_, _e_, _f_, etc.). The volume state will be `Rebuild` during the process, which may take several hours depending on the data stored on the disk. You can check the status in DiskPart: ``` DISKPART> list volume Volume ### Ltr Label Fs Type Size Status Info ---------- --- ----------- ----- ---------- ------- --------- -------- * Volume 0 C Windows NTFS Mirror 447 GB Rebuild System ``` It is best not to restart the server until the rebuild process is complete.   ### Rebuilding the mirror (GPT partition scheme) At the command prompt, open DiskPart: ``` C:\Windows\system32> diskpart ``` **Important:** **WARNING:** DiskPart executes commands without issuing warnings or asking for confirmation. Any changes done in DiskPart are irreversible. Entering commands while the wrong disk or volume is selected may therefore cause immediate data loss and/or prevent your system from booting. We recommend to proceed with caution and double-check each command. #### #### Listing all disks and volumes ``` DISKPART> list disk Disk ### Status Size Free Dyn Gpt -------- ------------- ------- ------- --- --- Disk 0 Online 1863 GB 0 B * * Disk 1 Online 1863 GB 1863 GB Disk M0 Missing 0 B 0 B * DISKPART> list volume Volume ### Ltr Label Fs Type Size Status Info ---------- --- ----------- ----- ---------- ------- --------- -------- Volume 0 C Windows NTFS Mirror 1862 GB Failed Rd Boot Volume 1 EFI FAT32 Partition 350 MB Healthy System ``` In this example, `Disk 1` is a replacement drive that has been installed to replace the defective `Disk M0` which had been physically removed previously. **Note:** The following code sections are for illustration only, based on the example output above. You will need to adjust the instructions according to your actual configuration by replacing the values in the commands with your disk and volume identifiers. #### #### Removing the replaced disk from the configuration ``` DISKPART> select volume c Volume 0 is the selected volume. DISKPART> break disk M0 nokeep DiskPart successfully broke the mirror volume. DISKPART> list volume Volume ### Ltr Label Fs Type Size Status Info ---------- --- ----------- ----- ---------- ------- --------- -------- Volume 0 C Windows NTFS Simple 1862 GB Healthy Boot Volume 1 EFI FAT32 Partition 350 MB Healthy System DISKPART> select disk M0 Disk M0 is now the selected disk. DISKPART> delete disk DiskPart successfully deleted the missing disk. DISKPART> list disk Disk ### Status Size Free Dyn Gpt -------- ------------- ------- ------- --- --- Disk 0 Online 1863 GB 0 B * * Disk 1 Online 1863 GB 1863 GB DISKPART> list volume Volume ### Ltr Label Fs Type Size Status Info ---------- --- ----------- ----- ---------- ------- --------- -------- Volume 0 C Windows NTFS Simple 1862 GB Healthy Boot Volume 1 EFI FAT32 Partition 350 MB Healthy System ``` #### Initializing the replacement disk On the new disk, create default and mandatory partitions, reflecting the existing partitioning of the first disk: ``` DISKPART> select disk 1 Disk 1 is now the selected disk. DISKPART> clean DiskPart succeeded in cleaning the disk. DISKPART> convert gpt DiskPart successfully converted the selected disk to GPT format. DISKPART> select partition 1 Partition 1 is now the selected partition. DISKPART> delete partition override DiskPart successfully deleted the selected partition. DISKPART> create partition efi size=350 DiskPart succeeded in creating the specified partition. DISKPART> format quick fs=fat32 label=EFI 100 percent completed DiskPart successfully formatted the volume. DiskPart successfully formatted the volume. DISKPART> assign letter=t DiskPart successfully assigned the drive letter or mount point. DISKPART> create partition msr size=128 DiskPart succeeded in creating the specified partition. DISKPART> list partition Partition ### Type Size Offset ------------- ---------------- ------- ------- Partition 1 System 350 MB 1024 KB * Partition 2 Reserved 128 MB 351 MB ``` #### Recreating the mirror between the first and the second disk ``` DISKPART> select volume c Volume 0 is the selected volume. DISKPART> add disk 1 DiskPart succeeded in adding a mirror to the volume. DISKPART> list disk Disk ### Status Size Free Dyn Gpt -------- ------------- ------- ------- --- --- * Disk 0 Online 1863 GB 0 B * * Disk 1 Online 1863 GB 0 B * * ``` Repeat this step for each existing volume from `Disk 0` that you want to mirror on `Disk 1`, using the associated drive letter (i.e. _d_, _e_, _f_, etc.).   #### Recreating the boot environment and setting boot options for the second disk ``` DISKPART> select disk 0 Disk 0 is now the selected disk. DISKPART> list partition Partition ### Type Size Offset ------------- ---------------- ------- ------- Partition 1 System 350 MB 1024 KB Partition 2 Dynamic Reserved 1024 KB 351 MB Partition 3 Reserved 127 MB 352 MB Partition 4 Dynamic Data 1862 GB 479 MB Partition 5 Dynamic Data 71 KB 1863 GB DISKPART> select partition 1 Partition 1 is now the selected partition. DISKPART> assign letter=s DiskPart successfully assigned the drive letter or mount point. DISKPART> list volume Volume ### Ltr Label Fs Type Size Status Info ---------- --- ----------- ----- ---------- ------- --------- -------- Volume 0 C Windows NTFS Mirror 1862 GB Rebuild Boot * Volume 1 S EFI FAT32 Partition 350 MB Healthy System Volume 2 T EFI FAT32 Partition 350 MB Healthy Hidden DISKPART> exit Leaving DiskPart... ``` Back at the command prompt, copy the boot files from the boot (EFI) partition on the first disk (`Disk 0`) to the boot partition on the second disk (`Disk 1`). Type the following three commands and execute each one with `Enter`: ``` robocopy s:\ t:\ * /e /copyall /xf BCD.* /xd "System Volume Information" bcdedit /export t:\EFI\Microsoft\Boot\BCD bcdedit /store t:\EFI\Microsoft\Boot\BCD /set {bootmgr} device partition=t: ``` Then launch DiskPart again and run the following commands: ``` DISKPART> select volume s Volume 2 is the selected volume. DISKPART> remove DiskPart successfully removed the drive letter or mount point. DISKPART> select volume t Volume 1 is the selected volume. DISKPART> remove DiskPart successfully removed the drive letter or mount point. ``` The volume state will be `Rebuild` during the process, which may take several hours depending on the data stored on the disk. You can check the status in DiskPart: ``` DISKPART> list volume Volume ### Ltr Label Fs Type Size Status Info ---------- --- ----------- ----- ---------- ------- --------- -------- Volume 0 C Windows NTFS Mirror 1862 GB Rebuild Boot Volume 1 EFI FAT32 Partition 350 MB Healthy Hidden Volume 2 EFI FAT32 Partition 350 MB Healthy System ``` It is best not to restart the server until the rebuild process is complete.   ## Go further Browse all the [Dedicated Servers guides](https://docs.us.ovhcloud.com/en/bare-metal-cloud/dedicated-servers/landing-page-dedicated-servers.md). Browse the rest of the [OVHcloud US documentation](https://docs.us.ovhcloud.com/en/index.md) for guides on our other products and services. Learn more about [Dedicated Servers](https://us.ovhcloud.com/bare-metal/) on the OVHcloud US website.