Lesson 1: Using Fault-Tolerant Volumes

Microsoft Windows 2000 Server includes support for two types of fault-tolerant volumes: mirrored volumes and RAID-5 volumes. Similar to mirror sets and stripe sets with parity in Microsoft Windows NT Server 4.0, Windows 2000 fault-tolerant volumes write data on multiple disks. Understanding how to use fault-tolerant volumes can help to protect data in the event of a disk failure.

You can use fault tolerance to help protect data against disk failures. In Windows 2000 Server, you create mirrored and RAID-5 volumes from unallocated space by using the Create Volume wizard in Computer Management.

To create a mirrored or RAID-5 volume from unallocated space, you would do the following:

1. In Computer Management, expand Storage, if necessary, and then click Disk Management.
2. Right-click an area of unallocated space, and then click Create Volume.
3. Click Next, and then, on the Select Volume Type page, specify the type of volume to create.

Table 12.1 describes the additional options you can specify in the Create Volume wizard.

Table 12.1 Create Volume Wizard Options

Option	Description
Select Disks	The dynamic disks that will make up the volume. For mirrored volumes, you can select only two disks. For RAID-5 volumes, you must select at least three disks.
Volume Size	The amount of unallocated disk space to use on each selected dynamic disk.
Assign A Drive Letter Or Path	A drive letter or path for the volume that you are creating.
Format Volume	Formatting options for the volume.

4. After you specify the appropriate options, click Finish to create the volume.

To mirror an existing volume, you would do the following:

1. After you specify the appropriate options, click Finish to create the volume.
2. Select the second disk in the mirrored volume, and then click OK.

When one member of a mirrored volume fails, the other member continues to operate, though it is no longer fault tolerant. To prevent potential data loss, you must recover the mirrored volume as soon as possible. The status of the failed volume appears in Disk Management as Failed Redundancy, and one of the disks will appear as Offline, Missing, or Online (Errors). The method that you use to recover the mirrored volume depends on the status of the disk.

To recover a mirrored volume if the disk status is either Offline or Missing, you would do the following:

1. Ensure that the disk is attached to the computer and has power.
2. In the Disk Management window, right-click the disk that is identified as Missing or Offline, and then click Reactivate Disk.

The status of the disk should return to Healthy, and the mirrored volume should regenerate automatically.

To recover a mirrored volume if the disk status is Online (Errors), in the Disk Management window, right-click the disk, and then click Reactivate Disk. The status of the disk should return to Healthy, and the mirrored volume should regenerate automatically.

If the preceding procedures fail to reactivate the disk or if the status of the volume does not return to Healthy, you must replace the failed disk and reestablish the mirrored volume:

To create a new mirrored volume, you would do the following:

1. In the Disk Management window, right-click the mirrored volume on the failed disk, and then click Remove Mirror.
2. In the Remove Mirror dialog box, click the failed disk, and then click Remove Mirror.
3. Click Yes when prompted to confirm your choice.
4. Right-click the volume that you want to mirror, and then click Add Mirror.
5. Select the second disk in the mirrored volume, and then click OK.

When one member of a RAID-5 volume fails, the other members continue to operate, though the volume is no longer fault-tolerant. To prevent potential data loss, you must recover the RAID-5 volume as soon as possible.

The status of the failed volume appears in the Disk Management window as Failed Redundancy, and one of the disks will appear as Offline, Missing, or Online (Errors). The method that you use to recover the RAID-5 volume depends on the status of the disk.

To recover a RAID-5 volume if the disk status is either Offline or Missing, you would do the following:

1. Ensure that the disk is attached to the computer and has power.
2. In the Disk Management window, right-click the disk that is identified as Missing or Offline, and then click Reactivate Disk.

The status of the disk should return to Healthy, and the RAID-5 volume should regenerate automatically.

To recover a RAID-5 volume if the disk status is Online (Errors), in the Disk Management window, right-click the disk, and then click Reactivate Disk. The status of the disk should return to Healthy, and the RAID-5 volume should regenerate automatically.

If the preceding procedures fail to reactivate the disk or if the status of the volume does not return to Healthy, you must replace the failed disk and regenerate the RAID-5 volume.

To regenerate a RAID-5 volume using a different disk, you would do the following:

1. In the Disk Management window, right-click the RAID-5 volume on the failed disk, and then click Repair Volume.
2. In the Repair RAID-5 Volume dialog box, select the disk that will replace the failed disk in the RAID-5 volume, and then click OK.

The Microsoft Windows 2000 family of server products includes support for two types of fault-tolerant volumes: mirrored volumes and RAID-5 volumes. You can use fault tolerance to help protect data against disk failures. In Windows 2000 Server, you create mirrored and RAID-5 volumes from unallocated space by using the Create Volume wizard in the Storage node of Computer Management.

If one member of a mirrored volume fails, the other member will continue to operate, but it is no longer fault tolerant. The status of the failed volume appears in the Disk Management window as Failed Redundancy, and one of the disks will appear as Offline, Missing, or Online (Errors). If the disk status is either Offline or Missing, ensure that the disk is attached to the computer and has power.

To recover a mirrored volume, in the Disk Management window, right-click the disk that is identified as Offline, Missing, or Online (Errors), and then click Reactivate Disk. If the disk fails to reactivate or if the status of the volume does not return to Healthy, you must replace the failed disk and reestablish the mirrored volume. To create a new mirrored volume, use the Disk Management tool to remove the existing mirror and then to create a new mirror.

When one member of a RAID-5 volume fails, the other members continue to operate, though the volume is no longer fault-tolerant. The status of the failed volume appears in the Disk Management window as Failed Redundancy, and one of the disks will appear as Offline, Missing, or Online (Errors). If the disk status is either Offline or Missing, ensure that the disk is attached to the computer and has power.

To recover a RAID-5 volume, in the Disk Management window, right-click the disk that is identified as Offline, Missing, or Online (Errors), and then click Reactivate Disk. If the disk fails to reactivate or if the status of the volume does not return to Healthy, you must replace the failed disk and regenerate the RAID-5 volume. To regenerate a RAID-5 volume using a different disk, in the Disk Management console window, right-click the RAID-5 volume on the failed disk, and then click Repair Volume. In the Repair RAID-5 Volume dialog box, select the disk that will replace the failed disk in the RAID-5 volume, and then click OK.