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Partition and Disk Facts

Windows supports two different kinds of disks: basic and dynamic. The disk type controls characteristics about how partitions and volumes are defined.

Disk type	Description
Basic	Basic disks have the following characteristics: Basic disks use primary and extendedpartitions. Each physical disk can have up to four primary partitions, or three primary partitions and one extended partition. Logical drives are defined within an extended partition. The extended partition can be divided into multiple logical drives. You must create a logical drive in an extended partition before you can format and store data (the logical drive, not the partition is the storage unit). Basic disks are supported by MS-DOS and all Windows operating system versions. A basic disk only supports volumes made up of contiguous disk space. Basic disks store partition information in a portion of the master boot record (MBR) known as the partition table. The partition table has room for up to four partition entries (hence the limitation on the number of primary partitions). When an extended partition is used, one of the four entries points to an extended boot record (EBR). The EBR is located within the extended partition, and contains information about the logical drives within the extended partition.
Dynamic	Dynamic disks have the following characteristics: Volumes on dynamic disks are like partitions and logical drives on basic disks. Dynamic disks support up to 128 volumes. Dynamic disks are supported by Windows 2000 and later. Dynamic disks support volumes that use discontiguous disk space. Simple volumes contain disk space from a single hard disk (both contiguous or discontiguous space). Spanned volumes contain disk space from multiple hard disks, grouped together into a single logical volume. Dynamic disks store partitioning information in a hidden database on all dynamic disks in the system.

Be aware of the following when managing partitions and volumes:

• Use Disk Management to create, format, and manage partitions and volumes.
• Basic and dynamic disks use the same hardware, but different partitioning methods.
• You can convert a basic disk to a dynamic disk without losing data in existing partitions.
  • Existing basic volumes and logical drives in the extended partition are converted to dynamic volumes.
  • You must reboot the system to complete the conversion if the disk contains the boot or system volume, or if the volume includes the pagefile.
  • To convert from a dynamic disk to a basic disk, you must delete all existing volumes.
• The activepartition identifies the partition that contains the operating system (or the program that loads the operating system) used to start the computer.
  • You can have only one active partition at a time.
  • The extended partition or a logical drive on the extended partition cannot be set to active.
• You cannot install the operating system on a dynamic disk. You can, however, upgrade a basic disk containing the operating system to a dynamic disk after installation.

When you first add a new disk, you must initialize the disk before you can create volumes. When you initialize the disk, you define the partition style to be used on the disk.

Adding Storage Facts

To add space to existing volumes, use one of the following strategies:

Method	Description
Configure a mount point	A mount pointis an empty folder on the existing volume that points to another partition. Data saved to the folder is physically saved on the referenced partition. The volume with the empty folder must be formatted with NTFS. You can create mount points on basic or dynamic volumes. The folder on the source volume must be empty. The target partition must not have a drive letter. Using a mount point is the only solution to adding space to the system volume using space on a different disk or non-contiguous disk space.
Extend the volume	When you extenda volume, you add unallocated disk space to the volume. For basic volumes, you can only extend the volume onto the same drive using contiguous unallocated space. Only Disk Management in Windows Vista or higher can extend basic volumes. Many third-party partitioning tools can extend partitions regardless of the operating system. To extend the volume onto the same drive using non-contiguous unallocated space, or to extend the volume onto another disk, convert the disk to a dynamic disk, then extend the volume. An extended volume uses disk space on the same disk. A spanned volume uses disk space on a different disk. The system volume can only be extended using contiguous free space on the same disk, and only when using Windows Vista. This is the same for both basic and dynamic disks. Volumes must be unformatted or formatted with NTFS to be extended.

RAID Configuration

RAID can be implemented in the following ways:

Method	Description
Hardware	Hardware RAID uses a special controller card that includes a RAID processor. Hardware RAID is the most expensive method, but provides much better performance than other methods.
Software	Software RAID uses a driver and the system CPU for controlling RAID operations. This is the slowest form of RAID. Some RAID controller cards support RAID configuration, but without the onboard RAID processor. These solutions are classified as software RAID (sometimes called fake RAID) even though you install a controller card to provide RAID capabilities. Many motherboards include built-in (onboard) support for RAID. RAID implemented in this way is typically software/driver RAID.
Operating system	Operating system RAID uses RAID features within the operating system. Like software RAID, the system CPU is used for RAID operations, but performance is typically better than software RAID because of integration with the operating system.

Windows desktop operating systems support creating RAID 0 arrays in Disk Management, but do not support configuring RAID 1 or RAID 5 arrays. To use RAID 1 or 5 on a client computer, you will need to use hardware or software RAID. The exact process you use to configure RAID depends on your motherboard and/or controller card. The following steps are a typical method for configuring software RAID included on many motherboards.

1. Install the RAID controller card and connect the drives to the controller. RAID arrays can use either IDE or SATA disks based on the type of disk supported by the controller card.
2. If using an onboard RAID controller with SATA drives, edit the CMOS settings and identify the drive type as RAID. This tells the system to load the onboard BIOS for accessing the connected drives.
3. Boot the computer. After the system BIOS loads, the RAID BIOS will load. Press the key combination displayed to enter the RAID configuration utility (commonly Ctrl + F).
4. Within the configuration utility, define an array, add disks to the array, and identify the array type (RAID 0, 1, or 5, etc.).
   • On some controller cards, you can create a RAID 1 set using an existing disk (with data) and a new disk. During the setup, data from the first disk is copied to the second disk.
   • Some controller cards cannot create mirrored drives using existing data on a drive. If you use drives with existing data, that data will be lost.
   • Some controller cards let you mirror an existing drive, but only from a utility that runs within the operating system.
   • When creating new RAID 0 and RAID 5 drives, all existing data on all disks will be lost.
5. Reboot the computer into the operating system and install the drivers for the RAID controller.
6. In Windows, the RAID array appears as a single disk with a partition already defined. Use Explorer or Disk Management to format the partition and assign it a drive letter.

If you want to install the operating system on a RAID array, follow steps 1-4 above, then take the following steps:

1. Reboot the computer from the operating system installation disc.
2. During the first part of the installation, Windows loads the necessary files it needs to start the installation. You will need to manually load the controller driver so that Windows can see the RAID array.
   • For Windows XP, press F6 when you see the message at the bottom of the screen to load a third party SCSI or RAID driver.
   • For Windows Vista/7, when asked to select the disk to install Windows, you will not see the RAID array in the list. Click the Load Driver link.
3. You will need to have the drivers on a floppy or USB disk.
4. After the drivers are loaded, select the partition that represents the RAID array. The installation process will format the partition and install the operating system.
5. Following installation, edit the CMOS settings to modify the boot order to boot from the RAID array. For arrays connected to a controller card, you will typically choose SCSI disk as the boot device (RAID arrays defined on a controller card typically appear in the BIOS as SCSI disks, even if IDE or SATA disks are used).

Disk Status

The following table describes various disk and volume statuses that you might encounter in Disk Management.

Status	Description
OnlineHealthy	The Online status indicates that the disk is turned on and can be accessed. The Healthy status indicates that a volume on the disk is valid and has no errors.
Formatting	Formatting is a status that shows for volumes during the formatting process. After formatting, the status for the volume changes to Healthy.
Unallocated	The Unallocated status shows for portions of a disk that have not been assigned to a partition or a volume.
No Media	The No Media status shows for an optical or removable media drive that does not contain a valid disc.
Initializing	The Initializing process shows while a disk is being converted from a basic disk to a dynamic disk. After the conversion, the status for the volume changes to Healthy.
Foreign	A Foreign disk is a dynamic disk that was created in one system and moved to another system. When you first add the disk to a different system, the partition information for the disk must be updated to reflect all dynamic disks in the current system. Import the disk to make it available in the new system.
Not InitializedUnknown	The Not Initialized or Unknown status indicates a disk without a valid master boot record or partition table (either missing or corrupt). To correct the problem, initialize the disk. If the partition table is invalid, use third party tools to try and recover the partition table.
Online (Errors)	The Online (Errors) status indicates that I/O errors have been detected on a dynamic disk. To correct the problem, try reactivating the disk.
MissingOffline	The Missing or Offline statuses show when a dynamic disk has failed, been removed, or turned off. If the disk is turned off, turn it back on, then reactivate the disk. If the disk no longer exists, then delete the disk from Disk Management.
Failed	The Failed status shows for a volume that cannot be started, such as when the disk is damaged or the file system is corrupt. Make sure the disk is on, then try reactivating the volume. If that doesn’t work, then you likely have data loss.
Unreadable	The Unreadable status indicates a hardware failure or I/O errors or other corruption, but might also be caused by a delay in reading the disk in Disk Management. Try rescanning the disk to see if the status changes; if not, troubleshoot the hardware or disk problem.

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Hope you remember all that!
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Gabe@networkdojo.net