Disk Storage Management
Windows Server 2008 supports two types of hard disk storage: basic and dynamic. All disks begin as basic disks until a server administrator converts them to dynamic status, one physical disk at a time. The biggest advantage that dynamic disks offer when compared to basic disks is that you can create software-based fault-tolerant volumes via the operating system from the volumes stored on dynamic disks (mirrored volumes/RAID 1 and Striping with Parity/RAID-5) volumes. Of course, you can always implement a hardware RAID solution by using a RAID controller and the disks can retain their basic status, or they can be converted to dynamic status under Windows Server 2008.
Basic Disks
A basic disk under Windows Server 2008 is essentially the same as the disk configuration under earlier versions of Windows: It is a physical disk with primary and extended partitions. Prior to Windows 2000, Microsoft did not call disks basic because that was the only type of disk available. There were no dynamic disks. As long as you use the File Allocation Table (FAT or FAT32) file system, Windows Vista, Windows XP, Windows 2000, Windows NT, Windows 9x, and the MS-DOS operating systems can access basic disks. You can create up to three primary partitions and one extended partition on a basic disk of four primary partitions. You can create a single extended partition with logical drives on a basic disk. Basic disks store their configuration information in the Partition Table, which is stored on the first sector of each hard disk. The configuration of a basic disk consists of the partition information on the disk.
Dynamic Disks
A Windows Server 2008 dynamic disk is a physical disk configuration that does not use partitions or logical drives, and the MBR is not used. Instead, the basic partition table is modified and any partition table entries from the MBR are added as part of the Logical Disk Manager (LDR) database that stores dynamic disk information at the end of each dynamic disk. Dynamic disks can be divided into as many as 2,000 separate volumes, but you should limit the number of volumes to 32 for each dynamic disk to avoid slow boot time performance.
Dynamic disks do not have the same limitations as basic disks. For example, you can extend a dynamic disk “on the fly” without requiring a reboot. Dynamic disks are associated with disk groups, which are disks that are managed as a collection. This managed collection of disks helps organize dynamic disks. All dynamic disks in a computer are members of the same disk group. Each disk in a disk group stores replicas of the same configuration data. This configuration data is stored in the 1MB LDR region at the end of each dynamic disk.
Dynamic disks support five types of volumes: simple, spanned, mirrored, striped, and RAID-5. You can extend a volume on a dynamic disk. Dynamic disks can contain a virtually unlimited number of volumes, so you are not restricted to four volumes per disk as you are with basic disks. Regardless of the type of file system, only computers running Windows Vista (Ultimate and Business Editions), Windows XP Professional, Windows 2000 Professional or Server, Windows Server 2003, or Windows Server 2008 can directly access dynamic volumes on hard drives that are physically connected to the computer. However, computers running other operating systems can access dynamic volumes remotely when they connect to shared folders over the network.
Managing Basic Disks and Dynamic Disks
When you install Windows Server 2008, the system automatically configures the existing hard disks as basic NTFS disks, unless they have been configured as dynamic from a previous installation. Windows Server 2008 does not support dynamic disks on mobile PCs (laptops or notebooks). If you’re using an older desktop machine that is not Advanced Configuration and Power Interface (ACPI) compliant, the Convert to Dynamic Disk option is not available. Dynamic disks have some additional limitations. You can install Windows Server 2008 on a dynamic volume that you converted from a basic disk, but you cannot extend either the system or the boot volume on a dynamic disk. Any troubleshooting tools that cannot read the dynamic disk management database work only on basic disks.
You can format partitions with the FAT16, FAT32, or NTFS on a basic or a dynamic disk. However, you can format a dynamic volume as NTFS only from the Disk Management console. You must use Windows Server 2008 Explorer to format a dynamic volume as FAT or FAT32.
When you install a fresh copy of Windows Server 2008 or when you perform an upgrade installation from Windows NT 4.0 Server with SP5, Windows 2000, or Windows Server 2003, the computer system defaults to basic disk storage. One or more of the disk drives could already be configured as dynamic if you upgraded from Windows 2000 Server, Windows Server 2003, or Windows Server 2008 (or if you import a “foreign disk” from a Windows 2000 Server or from another Windows Server 2003 computer). A disk is considered foreign when you move it from one computer to another computer, until you select the Import option for it in the Disk Management console.
Converting Basic Disks to Dynamic Disks
From the graphical user interface (GUI), you use the Windows Server 2008 Disk Management console (an MMC snap-in) to upgrade a basic disk to a dynamic disk. The Disk Management snap-in is located in the Computer Management console and the Server Management console. You must be a member of the local Administrators group or the backup operators group, or else the proper authority must be delegated to you if you are working within an Active Directory environment to make any changes to the computer’s disk management configuration.
For the conversion to succeed, any disks to be converted must contain at least 1MB of unallocated space. Disk Management automatically reserves this space when creating partitions or volumes on a disk, but disks with partitions or volumes created by other operating systems might not have this space available. (This space can exist even if it is not visible in Disk Management.) Windows Server 2008 requires this minimal amount of disk space to store the dynamic database, which the operating system that created it maintains. Before you convert any disks, close any programs that are running on those disks. After you convert a disk to dynamic, remember that you can have only one operating system that is bootable on each dynamic disk!
To convert a basic disk to a dynamic disk from the Disk Management console, follow these steps:
- Open the Disk Management console.
- Right-click the basic disk that you want to convert to a dynamic disk and click Convert to Dynamic Disk.
When you upgrade an empty basic disk to a dynamic disk, you do not need to reboot. However, if you convert a basic disk that already has partitions on it, or if the basic disk contains the system or boot partitions, you must restart your computer for the change to take effect.
To convert a basic disk to a dynamic disk from the Windows Server 2008 command line:
- Open a command prompt window, type diskpart, and press Enter.
- Type commands or help to view a list of available commands.
- Type select disk 0 to select the first hard disk (select disk 1 to select the second hard disk, and so on) and press Enter.
- Type convert dynamic and press Enter.
- Type exit to quit the diskpart.exe tool and then restart the computer to have the new configuration take effect.
When you convert a basic disk to a dynamic disk, any existing partitions on the basic disk become simple volumes on the dynamic disk. Any existing mirror sets, stripe sets, stripe sets with parity, or volume sets become mirrored volumes, striped volumes, dynamic RAID-5 volumes, or spanned volumes, respectively. After you convert a basic disk to a dynamic disk, you cannot change the volumes back to partitions. Instead, you must first delete all dynamic volumes on the disk, right-click the disk in Disk Management, and then select the Convert to Basic Disk option.
Because the conversion process from basic to dynamic is per physical disk, a disk has all dynamic volumes or all basic partitions; you won’t see both on the same physical disk. Remember, you do not need to restart your computer when you upgrade from an empty basic to a dynamic disk from the Disk Management console. However, you do have to restart your computer if you use the diskpart.exe command-line tool for the conversion; if you convert a disk containing the system volume, boot volume, or a volume with an active paging file; or if the disk contains any existing volumes or partitions.
Converting Dynamic Disks Back to Basic Disks
You must remove all volumes (and therefore all data) from a dynamic disk before you can change it back to a basic disk. After you convert a dynamic disk back to a basic disk, you can create only partitions and logical drives on that disk. After being converted from a basic disk, a dynamic disk can no longer contain partitions or logical drives, nor can older versions of Windows before Windows 2000 access the dynamic disk. To revert a dynamic disk to a basic disk, follow these steps:
- Back up the data on the dynamic disk.
- Open Disk Management.
- Delete all the volumes on the disk.
- Right-click the dynamic disk that you want to change back to a basic disk and then click Convert to Basic Disk.
- Restore the data to the newly converted basic disk.
Converting Basic Disks to GPT Disks
You can change a disk from MBR to GPT partition style as long as the disk does not contain any partitions or volumes. You cannot use the GPT partition style on removable media, or on cluster disks that are connected to shared SCSI or Fibre Channel buses that are used by the Cluster service.
Take these steps to change a master boot record disk into a GUID partition table disk within the Windows interface:
- Back up or move the data on the basic MBR disk you want to convert into a GPT disk.
- If the disk contains any partitions or volumes, right-click any volumes on the disk and then click Delete Partition or Delete Volume.
- Right-click the MBR disk that you want to change into a GPT disk and then click Convert to GPT Disk.
Take these steps to change a master boot record disk into a GUID partition table disk from a command line:
- Back up or move the data on the basic MBR disk you want to convert into a GPT disk.
- Open a command prompt and type diskpart. If the disk does not contain any partitions or volumes, skip to step 6.
- At the diskpart prompt, type list volume. Make note of the volume number you want to delete.
- At the diskpart prompt, type select volume <volumenumber>.
- At the diskpart prompt, type delete volume.
- At the diskpart prompt, type list disk. Make note of the disk number of the disk that you want to convert to a GPT disk.
- At the diskpart prompt, type select disk <disknumber>.
- At the diskpart prompt, type convert gpt.
Converting GPT Disks to Basic Disks
You can change a disk from GPT to MBR partition system as long as the disk is empty and contains no volumes. If it has data, you must back up your data and then delete all partitions or volumes before converting the disk.
To change a GUID partition table disk into a master boot record disk within the Windows interface, follow these steps:
- Back up or move all volumes on the basic GPT disk you want to convert into a MBR disk.
- If the disk contains any partitions or volumes, right-click any volumes on the disk and then click Delete Volume.
- Right-click the GPT disk that you want to change into an MBR disk and then click Convert to MBR disk.
To change a GUID partition table disk into a master boot record disk using the command line, follow these steps:
- Back up or move all volumes on the basic GPT disk you want to convert into a MBR disk.
- Open a command prompt and type diskpart. If the disk does not contain any partitions or volumes, skip steps 3-5.
- At the diskpart prompt, type list volume. Make note of the volume number you want to delete.
- At the diskpart prompt, type select volume <volumenumber>.
- At the diskpart prompt, type delete volume.
- At the diskpart prompt, type list disk. Make note of the disk number of the disk that you want to convert to a GPT disk.
- At the diskpart prompt, type select disk <disknumber>.
- At the diskpart prompt, type convert mbr.
Moving Disks to Another Computer
To move disks to another computer, follow these steps:
- Before you disconnect the disks, use Disk Management on the source computer and make sure that the status of all volumes on each of the disks is healthy. For any volumes that are not healthy, repair the volumes before you move the disks.
- If the disks are dynamic, right-click each disk and select Remove Disk.
- Power off the computer, remove the physical disks, and then install the physical disks on the target computer.
- When you restart the target computer, the Found New Hardware dialog box should appear. If not, click Start, Control Panel, Add Hardware to launch the Add Hardware Wizard. Use the wizard to properly install the disks on the computer.
- Open Disk Management on the target computer.
- Click Action, Rescan Disks from the menu bar.
- For any disks that are labeled Foreign, right-click them, click Import Foreign Disks, and then follow the instructions provided by the Disk Management console.
Reactivating a Missing or Offline Disk
A dynamic disk can become “missing” or “offline” when it is somehow damaged, it suddenly loses power, or it has its data cable disconnected while still powered on. Unfortunately, you can reactivate only dynamic disks—not basic disks.
Follow these steps to reactivate a missing or offline dynamic disk:
- Launch the Disk Management console.
- Right-click the disk marked Missing or Offline and then select the Reactivate Disk option.
- After the disk is reactivated, the disk should be labeled as “online.”
- Exit from the Disk Management MMC.