Introduction to Hard Drive Partition Types
Partitioning a drive is when you divide the total storage of a drive into different pieces. These pieces are called partitions. Once a partition is created, it can then be formatted so that it can be used on a computer. Partitioning enables a single hard drive to store more than one operating system (OS) or use as a backup for your files. One OS could be stored in one partition and another OS stored in a second, for example. Granted, most people use only one OS, but if you want to choose to boot Windows or Linux, partitions are the key to enabling you to do so.
You can install up to four different operating systems, each OS installed on its own primary partition, and boot to your choice each time you fire up the computer.
Windows support three different partitioning methods: the older but more universal master boot record (MBR) partitioning scheme and the newer (but proprietary to Microsoft) dynamic storage partitioning scheme. As of the mid 2010s, most new computers use the GUID Partition Table (GPT) partitioning scheme instead.
Microsoft calls a hard drive that uses the MBR partitioning scheme a basic disk and a drive using the dynamic storage partitioning scheme a dynamic disk . A single Windows system with two hard drives may have one of the drives partitioned as a basic disk and the other as a dynamic disk, and the system will run perfectly well.
Basic Disks
Basic disk partitioning creates two very small data structures on a drive, the master boot record (MBR) and a partition table , and stores them on the first sector of the hard drive called the boot sector . The MBR is nothing more than a tiny bit of code that takes control of the boot process from the system BIOS. When the computer boots to a hard drive, BIOS automatically looks for MBR code on the boot sector. The MBR has only one job: to look in the partition table for a partition with a valid operating system.
All basic disk partition tables support up to four partitions. The partition table supports two types of partitions: primary partitions and extended partitions. Primary partitions are designed to support bootable operating systems. Extended partitions are not bootable. A single basic disk may have up to three primary partitions and one extended partition.
Microsoft operating systems (DOS and Windows) traditionally assign primary partitions a drive letter from C: to Z:. Extended partitions do not get drive letters.
After you create an extended partition, you must create logical drives within that extended partition. A logical drive traditionally gets a drive letter from D: to Z:. The drive letter C: is always reserved for the first primary partition in a Windows PC. With the exception of the partition that stores the boot files for Windows (which will always be C:), any other primary partitions or logical drives may get either a drive letter or a folder on a primary partition.
Every primary partition on a single drive has a special setting called active stored in the partition table. This setting is either on or off on each primary partition. At boot, the MBR uses the active setting in the partition table to determine which primary partition to choose to try to load an Windows OS. Only one partition at a time can be the active partition , because you can run only one Windows OS at a time.
The boot sector at the beginning of the hard drive isn’t the only special sector on a hard drive. The first sector of the first cylinder of each partition also has a special sector called the volume boot sector . While the “main” boot sector defines the partitions, the volume boot sector stores information important to its partition, such as the location of the OS boot files.
Dynamic Disks
With the introduction of Windows 2000, Microsoft defined an entirely new type of partitioning called dynamic storage partitioning, better known as dynamic disks. Dynamic disks drop the word partition and instead use the term volume. A volume is still technically a partition, but it can do things a regular partition cannot do, such as spanning.
Remember that you were limited to four primary partitions when using basic disks. Dynamic disks simplify the process by treating all partitions as volumes, so you can make as many as you need.
A spanned volume goes across more than one drive. Windows allows you to span up to 32 drives under a single volume. Dynamic disks also support RAID 0, 1, and 5.
You can use five volume types with dynamic disks: simple, spanned, striped, mirrored, and RAID 5. Most folks stick with simple volumes. Simple volumes work much like primary partitions.
Spanned volumes use unallocated space on multiple drives to create a single volume. Spanned volumes are a bit risky?if any of the spanned drives fails, the entire volume is permanently lost.
Striped volumes are RAID 0 volumes. You may take any two unallocated spaces on two separate hard drives and stripe them. But again, if either drive fails, you lose all your data.
Mirrored volumes are RAID 1 volumes. You may take any two unallocated spaces on two separate hard drives and mirror them. If one of the two mirrored drives fails, the other will keep running.
RAID 5 volumes , as the name implies, are for RAID 5 arrays. A RAID 5 volume requires three or more dynamic disks with equal-sized unallocated spaces.
Dynamic disks use an MBR and a partition table, but these older structures are there only for backward compatibility. All of the information about a dynamic disk is stored in a hidden partition that takes up the last 1 MB of the hard drive.
GUID Partitioning Table (GPT) Disks
The GUID Partition Table disk architecture was introduced as part of the Extensible Firmware Interface initiative. GUID Partition Table is a new disk architecture that expands on the older Master Boot Record (MBR) partitioning scheme that has been common to Intel-based computers.
GUID Partition Table disks can grow to a very large size. As of July 2001, the Microsoft implementation supports a hard disk of up to 18 EB (512 KB LBAs).
The number of partitions on a GUID Partition Table disk is not constrained by temporary schemes such as container partitions as defined by the MBR Extended Boot Record. The Microsoft implementation of GUID Partition Table is limited to 128 partitions. However, it is important to note that one partition is used for the EFI System Partition, one for the Microsoft Reserved and two more are used if you use dynamic disks. This leaves 124 partitions for data use.
GUID Partition Table disks use primary and backup partition tables for redundancy and CRC32 fields for improved partition data structure integrity.
The 64-bit version of Windows XP can read and write MBR disks, but cannot boot from MBR disks.
Introducing Unified Extensible Firmware Interface (UEFI)
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You can install up to four different operating systems, each OS installed on its own primary partition, and boot to your choice each time you fire up the computer.
Windows support three different partitioning methods: the older but more universal master boot record (MBR) partitioning scheme and the newer (but proprietary to Microsoft) dynamic storage partitioning scheme. As of the mid 2010s, most new computers use the GUID Partition Table (GPT) partitioning scheme instead.
Microsoft calls a hard drive that uses the MBR partitioning scheme a basic disk and a drive using the dynamic storage partitioning scheme a dynamic disk . A single Windows system with two hard drives may have one of the drives partitioned as a basic disk and the other as a dynamic disk, and the system will run perfectly well.
Basic Disks
Basic disk partitioning creates two very small data structures on a drive, the master boot record (MBR) and a partition table , and stores them on the first sector of the hard drive called the boot sector . The MBR is nothing more than a tiny bit of code that takes control of the boot process from the system BIOS. When the computer boots to a hard drive, BIOS automatically looks for MBR code on the boot sector. The MBR has only one job: to look in the partition table for a partition with a valid operating system.
All basic disk partition tables support up to four partitions. The partition table supports two types of partitions: primary partitions and extended partitions. Primary partitions are designed to support bootable operating systems. Extended partitions are not bootable. A single basic disk may have up to three primary partitions and one extended partition.
Microsoft operating systems (DOS and Windows) traditionally assign primary partitions a drive letter from C: to Z:. Extended partitions do not get drive letters.
After you create an extended partition, you must create logical drives within that extended partition. A logical drive traditionally gets a drive letter from D: to Z:. The drive letter C: is always reserved for the first primary partition in a Windows PC. With the exception of the partition that stores the boot files for Windows (which will always be C:), any other primary partitions or logical drives may get either a drive letter or a folder on a primary partition.
Every primary partition on a single drive has a special setting called active stored in the partition table. This setting is either on or off on each primary partition. At boot, the MBR uses the active setting in the partition table to determine which primary partition to choose to try to load an Windows OS. Only one partition at a time can be the active partition , because you can run only one Windows OS at a time.
The boot sector at the beginning of the hard drive isn’t the only special sector on a hard drive. The first sector of the first cylinder of each partition also has a special sector called the volume boot sector . While the “main” boot sector defines the partitions, the volume boot sector stores information important to its partition, such as the location of the OS boot files.
Dynamic Disks
With the introduction of Windows 2000, Microsoft defined an entirely new type of partitioning called dynamic storage partitioning, better known as dynamic disks. Dynamic disks drop the word partition and instead use the term volume. A volume is still technically a partition, but it can do things a regular partition cannot do, such as spanning.
Remember that you were limited to four primary partitions when using basic disks. Dynamic disks simplify the process by treating all partitions as volumes, so you can make as many as you need.
A spanned volume goes across more than one drive. Windows allows you to span up to 32 drives under a single volume. Dynamic disks also support RAID 0, 1, and 5.
You can use five volume types with dynamic disks: simple, spanned, striped, mirrored, and RAID 5. Most folks stick with simple volumes. Simple volumes work much like primary partitions.
Spanned volumes use unallocated space on multiple drives to create a single volume. Spanned volumes are a bit risky?if any of the spanned drives fails, the entire volume is permanently lost.
Striped volumes are RAID 0 volumes. You may take any two unallocated spaces on two separate hard drives and stripe them. But again, if either drive fails, you lose all your data.
Mirrored volumes are RAID 1 volumes. You may take any two unallocated spaces on two separate hard drives and mirror them. If one of the two mirrored drives fails, the other will keep running.
RAID 5 volumes , as the name implies, are for RAID 5 arrays. A RAID 5 volume requires three or more dynamic disks with equal-sized unallocated spaces.
Dynamic disks use an MBR and a partition table, but these older structures are there only for backward compatibility. All of the information about a dynamic disk is stored in a hidden partition that takes up the last 1 MB of the hard drive.
GUID Partitioning Table (GPT) Disks
The GUID Partition Table disk architecture was introduced as part of the Extensible Firmware Interface initiative. GUID Partition Table is a new disk architecture that expands on the older Master Boot Record (MBR) partitioning scheme that has been common to Intel-based computers.
GUID Partition Table disks can grow to a very large size. As of July 2001, the Microsoft implementation supports a hard disk of up to 18 EB (512 KB LBAs).
The number of partitions on a GUID Partition Table disk is not constrained by temporary schemes such as container partitions as defined by the MBR Extended Boot Record. The Microsoft implementation of GUID Partition Table is limited to 128 partitions. However, it is important to note that one partition is used for the EFI System Partition, one for the Microsoft Reserved and two more are used if you use dynamic disks. This leaves 124 partitions for data use.
GUID Partition Table disks use primary and backup partition tables for redundancy and CRC32 fields for improved partition data structure integrity.
The 64-bit version of Windows XP can read and write MBR disks, but cannot boot from MBR disks.
Introducing Unified Extensible Firmware Interface (UEFI)
Did you find this tutorial helpful? Don’t forget to share your views with us.