MCSA Windows Server 2012 R2 Complete Study Guide. Panek William
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set fails, the entire volume fails.
■ Mirrored volume duplicates data across two disks. This type of volume is fault tolerant because if one drive fails, the data on the other disk is unaffected.
■ RAID-5 volume stores data in stripes across three or more disks. This type of volume is fault tolerant because if a drive fails, the data can be re-created from the parity off of the remaining disk drives. Operating system files and boot files cannot reside on the RAID-5 disks.
Exercise 1.5 illustrates the procedure for creating a volume set.
EXERCISE 1.5: Creating a Volume Set
1. Open Computer Management under Administrative Tools.
2. Select Disk Management.
3. Select and right-click a disk that has unallocated space. If there are no disk drives available for a particular volume set, that volume set will be grayed out as a selectable option. In this exercise, you’ll choose a spanned volume set, but the process after the volume set selection is the same regardless of which kind you choose. The only thing that differs is the number of disk drives chosen.
4. The Welcome page of the New Spanned Volume Wizard appears and explains the type of volume set chosen. Click Next.
5. The Select Disks page appears. Select the disk that will be included with the volume set and click Add. Repeat this process until all of the desired disks have been added. Click Next.
6. The Assign Drive Letter Or Path page appears. From here you can select the desired drive letter for the volume, mount the volume in an empty NTFS folder, or choose not to assign a drive letter. The new volume is labeled as E. Click Next.
7. The Format Volume page appears. Choose to format the new volume. Click Next.
8. Click Finish.
9. If the disks have not been converted to dynamic, you will be asked to convert the disks. Click Yes.
The new volume will appear as a healthy spanned dynamic volume with the new available disk space of the new volume set.
Storage Spaces in Windows Server 2012 R2
Windows Server 2012 R2 includes a technology called Storage Spaces. Windows Server 2012 R2 allows an administrator to virtualize storage by grouping disks into storage pools. These storage pools can then be turned into virtual disks called storage spaces.
The Storage Spaces technology allows an administrator to have a highly available, scalable, low-cost, and flexible solution for both physical and virtual installations. Storage Spaces allows you to set up this advantage on either a single server or in scalable multinode mode. So, before going any further, let’s look at these two terms that you must understand.
Storage Pools Storage pools are a group of physical disks that allows an administrator to delegate administration, expand disk sizes, and group disks together.
Storage Spaces Storage spaces allow an administrator to take free space from storage pools and create virtual disks called storage spaces. Storage spaces give administrators the ability to have precise control, resiliency, and storage tiers.
Storage spaces and storage pools can be managed by an administrator through the use of the Windows Storage Management API, Server Manager, or Windows PowerShell.
One of the advantages of using the Storage Spaces technology is the ability to set up resiliency. There are three types of Storage Space resiliency: mirror, parity, and simple (no resiliency).
Now that you understand what storage spaces and storage pools do, let’s take a look at some of the other advantages of using these features in Windows Server 2012 R2.
Availability One advantage to the Storage Spaces technology is the ability to fully integrate the storage space with failover clustering. This advantage allows administrators to achieve service deployments that are continuously available. Administrators have the ability to set up storage pools to be clustered across multiple nodes within a single cluster.
Tiered Storage The Storage Spaces technology allows virtual disks to be created with a two-tier storage setup. For data that is used often, you have an SSD tier; for data that is not used often, you use an HDD tier. The Storage Spaces technology will automatically transfer data at a subfile level between the two different tiers based on how often the data is used. Because of tiered storage, performance is greatly increased for data that is used most often, and data that is not used often still gets the advantage of being stored on a low-cost storage option.
Delegation One advantage of using storage pools is that administrators have the ability to control access by using access control lists (ACLs). What is nice about this advantage is that each storage pool can have its own unique access control lists. Storage pools are fully integrated with Active Directory Domain Services.
Redundant Array of Independent Disks
The ability to support drive sets and arrays using Redundant Array of Independent Disks (RAID) technology is built into Windows Server 2012 R2. RAID can be used to enhance data performance, or it can be used to provide fault tolerance to maintain data integrity in case of a hard disk failure. Windows Server 2012 R2 supports three types of RAID technologies: RAID-0, RAID-1, and RAID-5.
RAID-0 (Disk Striping) Disk striping is using two or more volumes on independent disks created as a single striped set. There can be a maximum of 32 disks. In a striped set, data is divided into blocks that are distributed sequentially across all of the drives in the set. With RAID-0 disk striping, you get very fast read and write performance because multiple blocks of data can be accessed from multiple drives simultaneously. However, RAID-0 does not offer the ability to maintain data integrity during a single disk failure. In other words, RAID-0 is not fault tolerant; a single disk event will cause the entire striped set to be lost, and it will have to be re-created through some type of recovery process, such as a tape backup.
RAID-1 (Disk Mirroring) Disk mirroring is two logical volumes on two separate identical disks created as a duplicate disk set. Data is written on two disks at the same time; that way, in the event of a disk failure, data integrity is maintained and available. Although this fault tolerance gives administrators data redundancy, it comes with a price because it diminishes the amount of available storage space by half. For example, if an administrator wants to create a 300GB mirrored set, they would have to install two 300GB hard drives into the server, thus doubling the cost for the same available space.
RAID-5 Volume (Disk Striping with Parity) With a RAID-5 volume, you have the ability to use a minimum of three disks and a maximum of 32 disks. RAID-5 volumes allow data to be striped across all of the disks with an additional block of error-correction called parity. Parity is used to reconstruct the data in the event of a disk failure. RAID-5 has slower write performance than the other RAID types because the OS must calculate the parity information for each stripe that is written, but the read performance is equivalent to a stripe set, RAID-0, because the parity information is not read. Like RAID-1, RAID-5 comes with additional cost considerations. For every RAID-5 set, roughly an entire hard disk is consumed for storing the parity information. For example, a minimum RAID-5 set requires three hard disks, and if those disks are 300GB each, approximately 600GB of disk space is available to the OS and 300GB is consumed by parity information, which equates to 33.3 percent of the available space. Similarly, in a five-disk RAID-5 set of 300GB disks, approximately 1,200GB of disk space is available to the OS, which means that 20 percent of the total available space is consumed by the parity information. The words roughly and approximately are used when calculating disk space because a 300GB disk will really be only about 279GB of space. This is because vendors define a gigabyte as 1 billion bytes, but the OS defines it as 230 (1,073,741,824) bytes. Also, remember that file systems and volume managers