Basic Volume


Definition of basic volume in Network Encyclopedia.

What are Volumes in Disk Management?

The highest level of organization in the file system is the volume. A file system resides on a volume. A volume contains at least one partition, which is a logical division of a physical disk. A volume that contains data that exists on one partition is called a simple volume, and a volume that contains data that exists on more than one partition is called a multipartition volume.

What is Basic Volume?

A type of volume in Microsoft Windows. A basic volume can be created only on a basic disk and can be:

  • A primary partition, extended partition, or logical drive that was created using the Disk Management portion of the Computer Management tool
  • A volume set, mirror set, stripe set, or stripe set with parity that was created using Windows NT version 4.0 or earlier

How Basic Disks and Volumes Work

Basic disks and volumes rely on the Logical Disk Manager (LDM) and Virtual Disk Service (VDS) and their associated components. These components enable you to perform tasks such as converting basic disks into dynamic disks, and creating fault-tolerant volumes. The following diagram shows the LDM and VDS components.

Logical Disk Manager and Virtual Disk Service Components

Basic disks and volumes can be managed using the Disk Management snap-in.

Basic disks can use either the master boot record (MBR) or GUID partition table (GPT) partitioning style. x86-based computers use disks with the MBR partitioning style and Itanium-based computers use disks with the GPT partitioning style.

Master Boot Record on Basic Disks

The master boot record (MBR), the most important data structure on the disk, is created when the disk is partitioned. The MBR contains a small amount of executable code called the master boot code, the disk signature, and the partition table for the disk. At the end of the MBR is a 2-byte structure called a signature word or end of sector marker, which is always set to 0x55AA. A signature word also marks the end of an extended boot record (EBR) and the boot sector.

The disk signature, a unique number at offset 0x01B8, identifies the disk to the operating system. Windows Server 2003 uses the disk signature as an index to store and retrieve disk information, such as drive letters, in the registry.

Master boot code

The master boot code performs the following activities:

  1. Scans the partition table for the active partition.
  2. Finds the starting sector of the active partition.
  3. Loads a copy of the boot sector from the active partition into memory.
  4. Transfers control to the executable code in the boot sector.

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