Windows Disk Settings Overview
When you install Windows Server 2012 R2 on a computer, the setup program automatically performs all the preparation tasks for the primary hard disk in the system. However, when you install additional hard disk drives on a server, or when you want to use settings that differ from the system defaults, you must perform the following tasks manually:
- Select a partitioning style Windows Server 2012 R2 supports two hard disk partition styles: the master boot record (MBR) partition style and the GUID (globally unique identifier) partition table (GPT) partition style. You must choose one of these partition styles for a drive; you cannot use both.
- Select a disk type Windows Server 2012 R2 supports two disk types: the basic disk type and the dynamic disk type. You cannot use both types on the same disk drive, but you can mix disk types in the same computer.
- Divide the disk into partitions or volumes Although many professionals use the terms partition and volume interchangeably, it is correct to refer to partitions on basic disks and volumes on dynamic disks.
- Format the partitions or volumes with a file system Windows Server 2012 R2 supports the NTFS file system, the FAT file system (including the FAT16, FAT32, and exFAT variants), and the new ReFS file system (covered later in this chapter, in the “Understanding file systems” section.)
The following sections examine the options for each of these tasks.
Selecting a partition style
The term partition style refers to the method that Windows operating systems use to organize partitions on the disk. Servers running Windows Server 2012 R2 computers can use either of the following two hard disk partition styles:
The MBR partition style has been around since before Windows and is still a common partition style for x86-based and x64-based computers.
GPT has existed since the late 1990s, but no x86 version of Windows prior to Windows Server 2008 and Windows Vista supports it. Today, most operating systems support GPT, including Windows Server 2012 R2.
Before Windows Server 2008 and Windows Vista, all x86-based Windows computers used only the MBR partition style. Computers based on the x64 platform could use either the MBR or GPT partition style, as long as the GPT disk was not the boot disk.
Unless the computer’s architecture provides support for an Extensible Firmware Interface (EFI)–based boot partition, it is not possible to boot from a GPT disk. If this is the case, the system drive must be an MBR disk and you can use GPT only on separate nonbootable disks for data storage
When you use Server Manager to initialize a disk in Windows Server 2012 R2, it uses the GPT partition style, whether it is a physical or a virtual disk. There are no controls in Server Manager supporting MBR, although it displays the partition style in the Disks tile.
Understanding disk types
Most personal computers use basic disks because they are the easiest to manage. Advanced volume types require the use of dynamic disks. A basic disk using the MBR partition style organizes data by using primary partitions, extended partitions, and logical drives. A primary partition appears to the operating system as though it is a physically separate disk and can host an operating system, in which case it is known as the active partition.
When you work with basic MBR disks in Windows Server 2012 R2 using the Disk Management snap-in, you can create three volumes that take the form of primary partitions. When you create the fourth volume, the system creates an extended partition, with a logical drive on it, of the size you specified. If there is free space left on the disk, the system allocates it to the extended partition, as shown in Figure 1, where you can use it to create additional logical drives.
FIGURE 1 Primary and extended partitions on a basic disk using MBR
When you select the GPT partition style, the disk still appears as a basic disk, but you can create up to 128 volumes, each of which appears as a primary partition, as shown in Figure 2. There are no extended partitions or logical drives on GPT disks.
FIGURE 2 Primary partitions on a basic disk using GPT
The alternative to using a basic disk is to convert it to a dynamic disk. The process of converting a basic disk to a dynamic disk creates a single partition that occupies the entire disk. You can then create an unlimited number of volumes out of the space in that partition.Dynamic disks support several different types of volumes, as described in the next section.
Understanding volume types
A dynamic disk can contain an unlimited number of volumes that function much like primary partitions on a basic disk, but you cannot mark an existing dynamic disk as active. When you create a volume on a dynamic disk by using the Disk Management snap-in in Windows Server 2012 R2, you choose from the following five volume types:
Consists of space from a single disk. After you have created a simple volume, you can extend it to multiple disks to create a spanned or striped volume, as long as it is not a system volume or boot volume. You can also extend a simple volume into any adjacent unallocated space on the same disk or, with some limitations, shrink the volume by deallocating any unused space in the volume.
Consists of space from 2 to 32 physical disks, all of which must be dynamic disks. A spanned volume is essentially a method for combining the space from multiple dynamic disks into a single large volume. Windows Server 2012 R2 writes to the spanned volume by filling all the space on the first disk and then filling each of the additional disks in turn. You can extend a spanned volume at any time by adding disk space. Creating a spanned volume does not increase the disk’s read/write performance or provide fault tolerance. In fact, if a single physical disk in the spanned volume fails, all the data in the entire volume is lost.
Consists of space from 2 to 32 physical disks, all of which must be dynamic disks. The difference between a striped volume and a spanned volume is that in a striped volume, the system writes data one stripe at a time to each successive disk in the volume. Striping provides improved performance because each disk drive in the array has time to seek the location of its next stripe while the other drives are writing.Striped volumes do not provide fault tolerance, however, and you cannot extend them after creation. If a single physical disk in the striped volume fails, all the data in the entire volume is lost.
Consists of an identical amount of space on two physical disks, both of which must be dynamic disks. The system performs all read and write operations on both disks simultaneously so they contain duplicate copies of all data stored on the volume. If one disk fails, the other continues to provide access to the volume until the failed disk is repaired or replaced.
Consists of space on three or more physical disks, all of which must be dynamic. The system stripes data and parity information across all the disks so that if one physical disk fails, the missing data can be re-created by using the parity information on the other disks. RAID-5 volumes provide improved read performance because of the disk striping, but write performance suffers due to the need for parity calculations.
Understanding file systems
To organize and store data or programs on a hard drive, you must install a file system. A file system is the underlying disk drive structure that enables you to store information on your computer. You install file systems by formatting a partition or volume on the hard disk.
In Windows Server 2012 R2, five file system options are available:
- FAT (also known as FAT16)
NTFS is the preferred file system for a server; the main benefits are improved support for larger hard drives than FAT and better security in the form of encryption and permissions that restrict access by unauthorized users.
Because the FAT file systems lack the security that NTFS provides, any user who gains access to your computer can read any file without restriction. Additionally, FAT file systems have disk size limitations: FAT32 cannot handle a partition greater than 32 GB or a file greater than 4 GB. FAT cannot handle a hard disk greater than 4 GB or a file greater than 2 GB. Because of these limitations, the only viable reason for using FAT16 or FAT32 is the need to dual boot the computer with a non-Windows operating system or a previous version of Windows that does not support NTFS, which is not a likely configuration for a server.
ReFS is a new file system first appearing in Windows Server 2012 R2 that offers practically unlimited file and directory sizes and increased resiliency that eliminates the need for errorchecking tools, such as Chkdsk.exe. However, ReFS does not include support for NTFS features such as file compression, Encrypted File System (EFS), and disk quotas. ReFS disks also cannot be read by any operating systems older than Windows Server 2012 and Windows 8.
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