Disks and volumes - jasper-zanjani/Windows-Server GitHub Wiki

Every track of a hard drive platter is split into disk sectors, traditionally 512 bytes. A block is commonly called an "allocation unit" in Windows, but also commonly called a cluster. Storage left over unused in partially unused blocks is known as slack space.

A new disk must first be initialized, that is, a partition table style must be chosen:

• GPT: 128 partitions per disk, maximum volume size of 18 exabytes (2⁶⁰ bytes). Booting from a GPT drive is not possible unless the computer architecture supports EFI-based boot partitions.
• MBR: older format that is commonly used for removable media, supporting volumes up to 2 TB with up to 4 primary partitions, although a common workaround is to make one of these partitions an extended partition, which can be be further subdivided into logical drives

Mounting a partition as a single filesystem produces a volume, although the distinction can often be lost. The exception would be a case where a volume spans multiple partitions or physical disks, as is possible with software RAID.

Virtual hard disks can be created with [Powershell][New-VHD] or in diskmgmt.msc and come in two formats:

• VHD
• VHDX

Only 2 filesystem options are available for modern servers:

• NTFS supports volumes up to 16 TB with the default 4 KB allocation unit size (but 256 TB with the 64 KB allocation unit size) and is required by some Windows Server services like AD DS, File Replication Service, Volume Shadow Copy Service, and Distributed File System
• ReFS uses the same system of permissions as NTFS and offers error checking and repair capabilities that NTFS does not, but it does not support NTFS features like file compression, Encrypted File System, and disk quotas. ReFS supports a maximum file size of 16 exabytes and volumes up to 1 yobibyte (2⁸⁰ bytes)

Software RAID can be implemented by creating Spanned, Striped, or RAID-5 volumes in diskmgmt.msc. A more modern and preferred technique is to create storage pools in [Storage Spaces][Storage Spaces].