Any disk using the MBR or GPT partition style can be configured as a dynamic disk. Unlike basic disks, which have basic volumes that can be created as primary partitions, extended partitions, and logical drives, dynamic disks have dynamic volumes that can be created as the following types:
Simple volumes A simple volume is a volume that's on a single drive and has the same purpose as a primary partition.
Spanned volumes A spanned volume is a volume that spans multiple drives.
Striped volumes A striped volume is a volume that uses RAID 0 to combine multiple disks into a stripe set.
Mirrored volumes A mirrored volume is a volume that uses RAID 1 to mirror a primary disk onto a secondary disk that is available for disaster recovery.
RAID-5 volumes A RAID-5 volume is a volume that uses RAID 5 to create a faulttolerant striped set on three or more disks.
Techniques for creating and managing these volume types are discussed in the sections that follow.
You create simple and spanned volumes in much the same way. The difference between the two is that a simple volume uses free space from a single disk to create a volume, while a spanned volume is used to combine the disk space on multiple disks to create the appearance of a single volume. If you later need more space, you can extend either volume type by using Disk Management. Here, you select an area of free space on any available disk and add it to the volume. When you extend a simple volume onto other disks, it becomes a spanned volume. Any volume that you want to expand should be formatted using NTFS because only NTFS volumes can be extended.
Simple and spanned volumes aren't fault tolerant. If you create a volume that spans disks and one of those disks fails, you won't be able to access the volume. Any data on the volume will be lost. You must restore the data from backup after you replace the failed drive and re-create the volume.
To create a simple or spanned volume, complete the following steps:
In Disk Management Graphical View, right-click an area marked Unallocated on a dynamic disk, and then choose New Volume. This starts the New Volume Wizard, as shown in Figure 19-11. Click Next.
Select Simple to create a volume on a single disk or Spanned to create a volume on multiple disks, and then click Next. You should see the Select Disks page shown in Figure 19-12. Use this page to select dynamic disks that should be part of the volume and to size the volume segments on the designated disks.
Select one or more disks from the list of dynamic disks that are available and have unallocated space. Click Add to add the disk or disks to the Selected list box. Next, select each of the disks in turn, then specify the amount of space you want to use on the selected disk. Click Next when you are ready to continue.
Use the Assign Drive Letter Or Path page shown in Figure 19-13 to assign a drive letter or path. You can also choose Do Not Assign A Drive Letter Or Drive Path if you want to create the partition without assigning a drive letter or path. Click Next.
Use the Format Volume page, as shown in Figure 19-14, to set the formatting options. Simple and spanned volumes can be formatted by using FAT, FAT32, or NTFS. If you think you might need to expand the volume at a later date, you might want to use NTFS because only volumes using NTFS can be expanded. If you opt not to format the partition at this time you can format the partition later as discussed in the section entitled "Formatting a Partition, Logical Drive, or Volume" earlier in this chapter.
Click Next. The final page shows you the options you've selected. If the options are correct, click Finish. The wizard then creates the volume and configures it.
Note
If you add volumes to a physical drive that contains the Windows Server 2003 operating system, you might inadvertently change the number of the boot volume. Windows Server 2003 will display a prompt warning you that the number of the boot volume will change. Click Yes to confirm this change. In most cases, Windows Server 2003 will make the appropriate changes in Boot.ini to ensure the system can be booted. To be sure, however, you should examine the Boot.ini file. It is located on the root directory of the system drive. You can determine the system drive by typing set systemdrive at the command prompt.
Unlike mirrors, striped, and RAID-5 volumes, which cannot be extended after they are created, both simple and spanned volumes can be extended. When you extend a simple or spanned volume, you add areas of free space either from the current disk or disks being used or from other disks to create a single volume.
Before you can extend a volume, the volume must be formatted as NTFS. You can convert FAT and FAT32 volumes to NTFS by using the CONVERT command discussed in the section entitled "Converting FAT or FAT32 to NTFS" earlier in this chapter. The volume also cannot be a boot or system volume, and there's a limitation of 32 disks for expansion, meaning a volume can span up to 32 disks, but no more. Additionally, you can't extend simple or spanned volumes that were upgraded from basic disks, either.
To extend a simple or spanned volume formatted as NTFS, complete the following steps:
In Disk Management Graphical View, right-click the volume you want to extend, and choose Extend Volume. This starts the Extend Volume Wizard, as shown in Figure 19-15. Click Next.
Use the Select Disks page shown in Figure 19-16 to select one or more disks from the list of dynamic disks that are available and have unallocated space. Click Add to add the disk or disks to the Selected list box. Afterward, select each of the disks in turn, then specify the amount of space you want to use on the selected disk. Click Next when you are ready to continue.
Click Next. The final page shows you the options you've selected. If the options are correct, click Finish. The wizard then extends the volume as appropriate.
Caution
Extended volumes aren't fault tolerant. If you create a volume that extends across multiple disks and one of those disks fails, you won't be able to access the volume, and any data on the volume will be lost. To recover, you must restore the data from backup after you replace the failed drive and re-create the volume.
Simple disks are the easiest to troubleshoot and recover because there is only one disk involved. Spanned disks, on the other, might have multiple disks, and the failure of any one disk makes the entire volume unusable. The drive status might show it is Missing, Failed, Online (Errors), Offline, or Unreadable.
The Missing (and sometimes Offline) status usually happens if drives have been disconnected or powered off. If the drives are part of an external storage device, check the storage device to ensure it is connected properly and has power. Reconnecting the storage device or turning on the power should make it so the drives can be accessed. You then must start Disk Management and rescan the missing drive. Right-click the missing drive, and choose Rescan Disks. When Disk Management finishes, right-click the drive, and then choose Reactivate.
The Failed, Online (Errors), and Unreadable statuses indicate input/output (I/O) problems with the drive. As before, try rescanning the drive, and then try to reactivate the drive. If the drive doesn't come back to the Healthy state, you might need to replace it.
One of the advantages of dynamic disks over basic disks is that you can easily move them from one computer to another. For example, if after setting up a server, you decide that you don't really need its two additional hard disk drives, you could move them to another server where they could be better used. Before you move disks, you should access Disk Management on the server where the dynamic disks are currently installed and check their status. The status should be Healthy. If it isn't, you should fix any problems before moving the disks.
Tip
Moving system disks requires additional planning
Before you move a system disk from one computer to another, you must ensure that the computers have identically configured hard disk subsystems. If they don't, the Plug and Play ID on the system disk from the original computer won't match what the new computer is expecting. As a result, the new computer won't be able to load the right drivers and boot will fail.
Next check to see whether any dynamic disks that you want to move are part of a spanned, extended, mirrored, striped, or RAID-5 set. If they are, you should make a note of which disks are part of which set and plan on moving all disks in a set together. If you are moving only part of a disk set, you should be aware of the consequences. For spanned, extended, or striped volumes, moving only part of the set will make the related volumes unusable on the current computer and on the computer to which you are planning to move the disks. If you plan to move only one disk of a mirrored volume, you should break the mirror before you move it. This ensures you can keep using the disks on both computers. For RAID-5 volumes, you should move all of the disks in the set if possible. If you move only part of the RAID-5 set, you might find that you can't use the set on either computer.
To move the disks, Start Computer Management and then in the left pane, select Device Manager. In the Device List, expand Disk Drives. This shows a list of all the physical disk drives on the computer. Right-click each disk that you want to move, and then select Uninstall. If you are unsure which disks to uninstall, right-click each disk and select Properties. In the Properties dialog box, select the Volumes tab, and then choose Populate. This shows you the volumes on the selected disk. In Computer Management, select Disk Management. Right-click each disk that you want to move, and then select Remove Disk.
Once you perform these procedures, you can move the dynamic disks. If the disk are hot swappable and this feature is supported on both computers, remove the disks from the original computer and then install them on the destination computer. Otherwise, turn off both computers, remove the drives from the original computer, and then install them on the destination computer. When you're finished, restart the computers. On the destination computer, access Disk Management, and then select Rescan Disks from the Action menu. When Disk Management finishes scanning the disks, right-click any disk marked Foreign, and click Import. You should now be able to access the disks and their volumes on the destination computer.
Note
When you move dynamic disks, the volumes on those disks should retain the drive letters they had on the previous computer. If a drive letter is already used on the destination computer, a volume receives the next available drive letter. If a dynamic volume previously did not have a drive letter, it does not receive a drive letter when moved to another computer. Additionally, if automounting is disabled, the volumes aren't automatically mounted and you must manually mount volumes and assign drive letters.
For RAID 1, disk mirroring, you configure two volumes on two drives identically. Data is written to both drives. If one drive fails, there is no data loss because the other drive contains the data. After you repair or replace the failed drive, you can restore full mirroring so that the volume is once again fault tolerant.
By using disk mirroring, you gain the advantage of redundancy. Because disk mirroring doesn't write parity information, mirrored volumes can usually offer better write performance than disk striping with parity. The key drawback, however, is that disk mirroring has a 50 percent overhead, meaning it effectively cuts the amount of storage space in half. For example, to mirror a 60-GB drive, you need another 60-GB drive. That means you use 120 GB of space to store 60 GB of information.
As with disk striping, you'll often want the mirrored disks to be on separate disk controllers. This provides redundancy for the disk controllers. If one of the disk controllers fails, the disk on the other controller is still available. When you use two separate disk controllers to duplicate data, you're using a technique known as disk duplexing rather than disk mirroring—but why mince words?
You can create a mirrored set either by using two new disks or by adding a mirror to an existing volume. As with other RAID techniques, mirroring is transparent to users. Users see the mirrored set as a single volume that they can access and use like any other drive.
To create a mirrored set using two new disks, start Disk Management. In Graphical View, right-click an area marked Unallocated on a dynamic disk, and then choose New Volume. This starts the New Volume Wizard. Click Next. Select Mirrored as the volume type. Create the volume as described in the section entitled "Creating a Simple or Spanned Volume" earlier in this chapter. The key difference is that you must create two identically sized volumes and these volumes must be on separate dynamic drives. The volumes can be formatted as FAT, FAT32, or NTFS. You won't be able to continue past the Selected Disks page until you've selected the two disks that you want to work with.
When you click Finish, you'll return to the main Disk Management window, and Disk Management will create the mirrored set. During the creation of the mirror, you'll see a status of Resynching, as shown in Figure 19-17. This tells you that Disk Management is creating the mirror. When this process finishes, you'll have two identical volumes. Both volumes will show the same drive letter in Disk Management, but the separation of volumes is transparent to users. Users see the mirror set as a single volume. The volume status should be listed as Healthy. This is the normal status for volumes. If the status changes, you might need to repair or resync the mirrored set, as discussed in the section entitled "Resolving Problems with Mirrored Sets" later in this chapter.
You can also use an existing volume to create a mirrored set. For this to work, the volume you want to mirror must be a simple volume and you must have an area of unallocated space on a second dynamic drive of equal or larger space than the existing volume. When you add a mirror onto this unallocated space, Disk Management creates a volume that is the same size and file system type as the simple volume you are mirroring. It then copies the data from the simple volume to the new volume using a process called resynching.
To add a mirror to an existing volume, start Disk Management. In Graphical View, right-click the simple volume you want to mirror, and then select Add Mirror. This displays the Add Mirror dialog box. Use the Disks list to select a location for the mirror, and then click Add Mirror. Windows Server 2003 begins the mirror creation process, and you'll see a status of Resynching on both volumes.
When the resynching is complete, you have two identical copies of the original volume. Although both volumes show the same drive letter in Disk Management, the separation of volumes is transparent to users. Users see the mirror set as a single volume.
Disk mirroring is often used to mirror boot and system volumes. Mirroring these volumes ensures that you'll be able to boot the server in case of a single drive failure.
When you want to mirror boot or system volumes on MBR disks, the process is fairly straightforward. You start with two disks, which I'll call Disk 0 and Disk 1, where Disk 0 has the system files and Disk 1 is a new disk. Because Setup won't let you install Windows Server 2003 on a dynamic disk, the system disk is typically a basic disk that must be upgraded to a dynamic disk before you can mirror it—mirroring is only possible on dynamic disks.
To begin, upgrade Disk 0 to a dynamic disk and then upgrade Disk 1 as discussed in the section entitled "Using and Converting Basic and Dynamic Disks" earlier in this chapter. In Disk Management, right-click the boot or system volume that you want to mirror, and then select Add Mirror. This displays the Add Mirror dialog box. Select the disk onto which you want to add the mirror (Disk 1 in the example), and then click Add Mirror. Windows Server 2003 begins the mirror creation process, and you'll see a status of Resynching on both volumes. When the resynching is complete, the status should change to Healthy.
During the creation of the mirror, Windows Server 2003 adds an entry on the Boot menu for the second volume and labels it "Boot Mirror—Secondary Plex." If the primary mirror fails, you can use this entry to boot the computer to the second volume as discussed in the section entitled "Repairing a Mirrored System Volume to Enable Boot" later in this chapter.
Mirroring boot and system volumes on GPT disks isn't the same as for MBR disks. Primarily, this is because GPT disks used to boot the operating system have an ESP and an MSR partition that must be created on the disk in a certain order. Thus, to mirror boot and system volumes on GPT disks, you must create the necessary partitions on the second disk of the mirrored set and tell the operating system that these partitions can be used for booting.
To get started, you need two disks that use the GPT partition style and the basic storage type. One of the disks should already be designated as the boot volume. I'll refer to this volume as Disk 0. The other disk should be identical in size or larger than the boot volume. I'll refer to this volume as Disk 1. Disk 1 should be a clean disk, meaning it can't already have partitions on it; so, if necessary, copy any data on the disk to another disk or make a backup of the data and then delete any existing partitions. You can use DiskPart to do this by completing the following steps:
At the command prompt, invoke DiskPart by typing diskpart. List the disks available on the system by typing list disk.
Select the disk you are going to use as the secondary boot disk. Following the example, this is Disk 1, so you would type select disk 1.
List the partitions on this disk by typing list partition.
If there are any existing partitions, select and delete each partition in turn. For example, if the disk had Partition 1, you'd type select partition 1, and then type delete partition override. The Override parameter ensures that you can delete nonuser partitions.
Once you've made sure the second disk doesn't contain any partitions, list the available disks again by typing list disk, then select the disk you are going to use as the current boot disk. Following the example, this is Disk 0, so you would type select disk 0. List the partitions on this disk by typing list partition. The output you'll see will be similar to the following:
Partition ### Type Size Offset ------------- ---------------- ------- ------- Partition 1 System 316 MB 32 KB Partition 2 Primary 9992 MB 312 MB Partition 3 Reserved 32 MB 9 GB
The output shows you which partitions are being used as the ESP and MSR partition. The ESP is listed with the partition type System. The MSR partition is listed with the partition type Reserved. Note the size of each partition. Here, System is 316 MB and Reserved is 32 MB.
You now must create the ESP and the MSR partition on the second disk by completing the following steps:
In DiskPart, select this disk to give it focus. Following the example, you'd type select disk 1.
Afterward, you would create the ESP first by typing create partition efi size=N, where N is the size previously noted, such as size=316.
Create the MSR partition by typing create partition msr size=N, where N is the size previously noted, such as size=32.
If you type list partition, you should see that both partitions have been created and are sized appropriately, such as follows:
Partition ### Type Size Offset ------------- ---------------- ------- ------- Partition 1 System 316 MB 32 KB Partition 2 Reserved 32 MB 316 MB
Next you must prepare the ESP for use by assigning it a drive letter, formatting it, and copying over the necessary startup files from the current boot volume. To do this, follow these steps:
In DiskPart, select the partition by typing select partition 1.
Assign a drive letter by typing assign letter=X, where X is the drive letter, such as letter=H.
Exit DiskPart by typing exit.
Format the ESP as FAT using the drive letter you just assigned. Following the example, you'd type format h: /fs:fat /q /y.
Once formatting is complete, invoke DiskPart by typing diskpart, and then select the current boot volume. Following the example, you'd type select disk 0.
Type select partition 1 to select the ESP on the current boot volume.
Assign this partition a drive letter by typing assign letter=X, where X is the drive letter to assign, such as letter=I.
Exit DiskPart by typing exit.
Use the XCOPY command to copy all the files from the ESP on the current boot volume to the ESP on the second disk. Following the example, you'd type xcopy i:*.* h: /s /h. The /S and /H parameters ensure that hidden system files are copied.
You now must convert both drives to the dynamic storage type. Start with the second disk and then convert the current boot disk. Follow these steps:
Invoke DiskPart by typing diskpart.
Select the disk you are going to use as the secondary boot disk. Following the example, this is Disk 1, so you would type select disk 1.
Convert the disk by typing convert dynamic.
Select the current boot disk. Following the example, this is Disk 1, so you would type select disk 0.
Convert the disk by typing convert dynamic.
Exit DiskPart by typing exit.
You must shut down and restart the computer to complete the conversion process for the current boot disk. In some cases, this process takes several reboots to complete.
Note
You don't have to delete the drive letters assigned in the previous procedure. These drive letters will not be reassigned after the restart.
When the conversion process is complete, log on to the system, and then follow these steps to mirror the boot drive:
Invoke DiskPart by typing diskpart.
Select the current boot disk. Following the example, this is Disk 1, so you would type select disk 0.
Add the disk to use as the second drive to this volume to create the mirrored set. Following the example, you'd type add disk=1.
DiskPart will then begin the mirror creation process by synchronizing the data on both volumes.
During the creation of the mirror, Windows Server 2003 adds an entry on the Boot menu for the second volume and labels it "Boot Mirror—Secondary Plex." If the primary mirror fails, you can use this entry to boot the computer to the second volume, as discussed in the section entitled "Repairing a Mirrored System Volume to Enable Boot" later in this chapter. However, this doesn't protect you from complete failure of the primary boot disk. Why? Because you haven't told the operating system about the ESP on the second disk.
To tell the operating system about the ESP on the second disk and safeguard the system against complete failure of the primary boot disk, you clone the ESPs on the primary and secondary boot disks, and thereby create new entries that allow the system to boot from the secondary boot disk regardless of whether the primary boot disk is available. Follow these steps:
List the current boot entries for the computer by typing bootcfg at the command prompt. The output shows you the current default boot device and the configuration of each boot entry, as follows:
Boot Loader Settings -------------------- timeout: 30 default: DeviceHarddiskDmVolumesPhysicalDmVolumesBlockVolume1WIN03 CurrentBootEntryId: 1 Boot Entries ------------ Boot entry ID: 1 OS Friendly Name:Windows 2003 Server, Enterprise OsLoadOptions: N/A BootFilePath: DeviceHarddiskVolume1EFIMicrosoftWINNT50ia64ldr.efi OsFilePath: DeviceHarddiskDmVolumesPhysicalDmVolumesBlockVolume1WIN03 Boot entry ID: 2 OS Friendly Name:CDROM Boot entry ID: 3 OS Friendly Name:EFI Shell Boot entry ID: 4 OS Friendly Name:Boot Mirror D: - secondary plex OsLoadOptions: N/A BootFilePath: DeviceHarddiskVolume1EFIMicrosoftWINNT50ia64ldr.efi OsFilePath: DeviceHarddiskDmVolumesPhysicalDmVolumesBlockVolume1WIN03
Display the boot entry details of each partition on the primary boot disk. Following the example, you'd type bootcfg /list 0. The partition listings look like this:
Partition No: 1 Partition Style: GPT Starting offset: 32,256 Partition length: 211,000,512 Partition GUID: {344b23d1-003b-125c-3522-5e2c34515322} GUID type: {d01b1234-d234-e235-b34a-00b12c34234a} Partition name: EFI system partitionCopy the GUID of the ESP to the Clipboard and paste it into a Notepad window. Here, you would copy {344b23d1-003b-125c-3522-5e2c34515322} and paste it to Notepad. This is the source GUID value needed to clone the boot entry.
Display the boot entry details of each partition on the secondary boot disk. Following the example, you'd type bootcfg /list 1. As before, copy the GUID of the ESP to the Clipboard and paste it into a Notepad window. This is the target GUID value needed to clone the boot entry.
Use the BOOTCFG /CLONE command to create the boot entries needed to boot to the secondary boot disk. Type bootcfg /clone /sg SourceGUID /tg TargetGUID /d+ Secondary_Boot, where SourceGUID is the GUID for the primary boot disk and TargetGUID is the GUID for the secondary boot disk. Paste or type in the GUIDs carefully, making sure to include the curly braces {}.
Before you press Enter, ensure the syntax is exact and that the GUIDs are correctly entered. This command creates two boot entries, one for the source and one for the target. BOOTCFG will report the status of each, and the output should report success, as follows:
INFO: Boot entry whose id is '1' successfully cloned. INFO: Boot entry whose id is '4' successfully cloned. SUCCESS: The operation completed successfully.
Here, BOOTCFG reports that it successfully cloned boot entries 1 and 4. These entries should be added to the Boot menu with the next available ID. In this case, that would be if you typed bootcfg again, you'd see the additional entries, as follows:
Boot entry ID: 5 OS Friendly Name: Windows 2003 Server, Enterprise Secondary_Boot OsLoadOptions: N/A BootFilePath: DeviceHarddiskVolume2EFIMicrosoftWINNT50ia64ldr.efi OsFilePath: DeviceHarddiskDmVolumesPhysicalDmVolumesBlockVolume1WIN03 Boot entry ID: 6 OS Friendly Name: Boot Mirror D: - secondary plex Secondary_Boot OsLoadOptions: N/A BootFilePath: DeviceHarddiskVolume2EFIMicrosoftWINNT50ia64ldr.efi OsFilePath: DeviceHarddiskDmVolumesPhysicalDmVolumesBlockVolume1WIN03
Note
The boot file path (BootFilePath) of the cloned entry points to a different hard disk drive than the original entries. This is as expected, because these entries are for the secondary disk.
Now if you shut down the system and restart, you should be able to boot successfully to either the primary or secondary boot disk.
RAID 5, disk striping with parity, offers fault tolerance with less overhead and better read performance than disk mirroring. To configure RAID 5, you use three or more volumes, each on a separate drive, as a striped set, similar to RAID 0. Unlike RAID 0, however, RAID 5 adds parity error checking to ensure that the failure of a single drive won't bring down the entire drive set. In the event of a single drive failure, the set continues to function with disk operations directed at the remaining disks in the set. The parity information can also be used to recover the data using a process called regeneration.
RAID 5 works like this: Each time the operating system writes to a RAID-5 volume, the data is written across all the disks in the set. Parity information for the data, used for error checking and correction, is written to disk as well, but always on a separate disk from the one used to write the data. For example, if you are using a three-volume RAID-5 set and save a file, the individual data bytes of the file are written to each of the disks in the set. Parity information is written as well, but not to the same disk as one of the individual data bytes. Thus, a disk in the set could have a chunk of the data or the corresponding parity information, but not both, and this in turn means that the loss of one disk from the set doesn't cause the entire set to fail.
Like any type of RAID, RAID 5 has its drawbacks as well. First, if multiple drives in the set fail, the entire set will fail and you won't be able to regenerate the set from the parity information. Why? If multiple drives fail, there won't be enough parity information to use to recover the set. Second, having to generate and write parity information every time data is written to disk slows down the write process (and, in the case of software RAID, processing power). To compensate for the performance hit, hardware RAID controllers have their own processors that handle the necessary processing—and this is why hardware RAID is preferred over software RAID.
Okay, so RAID 5 gives you fault tolerance at some cost to performance. It does, however, have less overhead than RAID 1. By using RAID 1, you have a 50 percent overhead, which effectively cuts the amount of storage space in half. By using RAID 5, the overhead depends on the number of disks in the RAID set. With three disks, the overhead is about one-third. If you had three 60-GB drives using RAID 5, you'd use 180 GB of space to store about 120 GB of information. If you have additional disks, the overhead is reduced incrementally, but not significantly.
To create a RAID-5 set, start Disk Management. In Graphical View, right-click an area marked Unallocated on a dynamic disk, and then choose New Volume. This starts the New Volume Wizard. Click Next. Select RAID 5 as the volume type. Create the volume as described in the section entitled "Creating a Simple or Spanned Volume" earlier in this chapter. The key difference is that you must select free space on three or more separate dynamic drives.
When you click Finish, you'll return to the main Disk Management window and Disk Management will create the RAID-5 set. During the creation of the mirror, you'll see a status of Resynching. This tells you that Disk Management is creating the RAID-5 set. When this process finishes, you'll have three or more identical volumes, all of which will show the same drive letter in Disk Management. Users, however, will see the RAID-5 set as a single volume. The volume status should be listed as Healthy. This is the normal status for volumes. If the status changes, you might need to repair or regenerate the RAID-5 set as discussed in the section entitled "Resolving Problems with RAID-5 Sets" later in this chapter.
Windows Server 2003 provides two ways to stop mirroring. You can break a mirrored set, creating two separate but identical volumes. Or you can remove a mirror, which deletes all the data on the removed mirror.
To break a mirrored set, follow these steps:
In Disk Management, right-click one of the volumes in the mirrored set, and then choose Break Mirrored Volume.
Confirm that you want to break the mirrored set by clicking Yes. If the volume is currently in use, you'll see another warning dialog box. Confirm that it's okay to continue by clicking Yes.
Windows Server 2003 will then break the mirrored set, creating two independent volumes.
To remove a mirror, follow these steps:
In Disk Management, right-click one of the volumes in the mirrored set, and then choose Remove Mirror. This displays the Remove Mirror dialog box.
In the Remove Mirror dialog box, select the disk from which to remove the mirror. If the mirror contains a boot or system volume, you should remove the mirror from the secondary drive rather than the primary. For example, if Drive 0 and Drive 1 are mirrored, remove Drive 1 rather than Drive 0.
Confirm the action when prompted. All data on the removed mirror is deleted.
Occasionally, data on mirrored volumes can get out of sync. Typically, this happens if one of the drives in the set goes offline or experiences temporary I/O problems and, as a result, data can be written only to the drive that's online. To reestablish mirroring, you must get both drives online and then resynchronize the mirror. The corrective action you take depends on the drive status.
The Missing or Offline status usually happens if drives have been disconnected or powered off. If the drives are part of an external storage device, check the storage device to ensure it is connected properly and has power. Reconnecting the storage device or turning on the power should make it so the drives can be accessed. You then must start Disk Management and rescan the missing drive. Right-click the missing drive, and choose Rescan Disks. When Disk Management finishes, right-click the drive, and choose Reactivate. The drive status should change to Regenerating and then to Healthy. If the volume doesn't return to the Healthy status, right-click the volume, and then click Resynchronize Mirror.
A status of Failed, Online (Errors), or Unreadable indicates I/O problems with the drive. As before, try rescanning the drive, and then try to reactivate the drive. The drive status should change to Regenerating and then to Healthy. If the volume doesn't return to the Healthy status, right-click the volume, and then click Resynchronize Mirror.
If these actions don't work, you must remove the failed mirror, replace the bad drive, and then rebuild the mirror. To do this, follow these steps:
Right-click the failed volume, and then select Remove Mirror.
You now must mirror the volume on an Unallocated area of free space on a different disk. If you don't have free space, you must create space by deleting other volumes or replacing the failed drive.
When you are ready to continue, right-click the remaining volume in the original mirror, and then select Add Mirror. This displays the Add Mirror dialog box.
Use the Disks list to select a location for the mirror, and then click Add Mirror. Windows Server 2003 begins the mirror creation process, and you'll see a status of Resynching on both volumes.
When you mirror a system volume, an entry that allows you to boot to the secondary mirror is added to the system's Boot.ini file. So, if a system fails to boot to the primary system volume, restart the system, and select the Boot Mirror—Secondary Plex option for the operating system you want to start. The system should start up normally. Once you successfully boot the system to the secondary drive, you can schedule the maintenance necessary to rebuild the mirror if desired.
To rebuild the mirror, you must complete the following steps:
Shut down the system and replace the failed drive, and then restart the system using the secondary drive.
In Disk Management, right-click the remaining volume in the mirrored set, and choose Break Mirrored Volume. Click Yes at the prompts to confirm the action.
Next, right-click the volume again, and choose Add Mirror. Use the Add Mirror dialog box to select the second disk to use for the mirror, and then click Add Mirror.
Check Boot.ini to ensure that the designated boot volumes are correct.
If you want the primary mirror to be on the drive you added or replaced, perform these additional steps:
Use Disk Management to break the mirrored set again.
Make sure that the primary drive in the original mirror set has the drive letter that was previously assigned to the complete mirror. If it doesn't, assign the appropriate drive letter.
Right-click the original system volume, select Add Mirror, and then re-create the mirror.
Check Boot.ini to ensure that the original system volume is used during startup.
For GTP disks, rebuilding mirrored system volumes is a bit different. To rebuild the mirror, shut down the system and replace the failed drive, and then restart the system using the secondary drive. In Disk Management, right-click the remaining volume in the mirrored set, and choose Break Mirrored Volume. Click Yes at the prompts to confirm the action. After this, you can use the secondary boot disk as your primary boot disk and follow the procedures outlined in the section entitled "Mirroring Boot and System Volumes on MBR Disks" earlier in this chapter to reenable mirroring properly using the secondary disk as the primary.
Most problems with RAID-5 sets have to do with the intermittent or permanent failure of a drive. If one of the drives in the set goes offline or experiences temporary I/O problems, parity data cannot be properly written to the set and, as a result, the set's status will show as Failed Redundancy and the failed volume's status changes to Missing, Offline, or Online (Errors).
You must get all drives in the RAID-5 set online. If the status of the problem volume is Missing or Offline, make sure that the drive has power and is connected properly. You then must start Disk Management and rescan the missing drive. Right-click the missing drive, and choose Rescan Disks. When Disk Management finishes, right-click the drive, and choose Reactivate. The drive status should change to Regenerating and then to Healthy. If the volume doesn't return to the Healthy status, right-click the volume, and then click Regenerate Parity.
A status of Failed, Online (Errors), or Unreadable indicates I/O problems with the drive. As before, try rescanning the drive, and then try to reactivate the drive. The drive status should change to Regenerating and then to Healthy. If the volume doesn't return to the Healthy status, right-click the volume, and then click Regenerate Parity.
If one of the drives still won't come back online, you must repair the failed region of the RAID-5 set. Right-click the failed volume, and then select Remove Volume. You now must right-click an unallocated space on a separate dynamic disk and choose Repair Volume. This space must be at least as large as the region to repair, and it can't be on a drive that's already being used by the RAID-5 set. If you don't have enough space, the Repair Volume option is unavailable and you must free space by deleting other volumes or replacing the failed drive.