Windows 7

Working with Volume Sets

A volume set is created from volumes that span multiple drives by using the free space from those drives to construct what will appear to be a single drive. The following list includes the various types of volume sets and their definitions:

Simple volume uses only one disk or a portion of a disk.
Spanned volume is a simple volume that spans multiple disks, with a maximum of 32. Use a spanned volume if the volume needs are too great for a single disk.
Striped volume stores data in stripes across two or more disks. A striped volume gives you fast access to data but is not fault tolerant, nor can it be extended or mirrored. If one disk in the striped 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.

Creating a Volume Set

Open Computer Management under Administrative Tools.
Select Disk Management.
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 section, 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.
The Welcome page of the New Spanned Volume Wizard appears and explains the type of volume set chosen. Click Next.
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.
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.
The Format Volume page appears. Choose to format the new volume. Click Next.
Click Finish.
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.

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. 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 supports three different 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 off of 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 300 GB mirrored set, they would have to install two 300 GB 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 300 GB each, approximately 600 GB of disk space is available to the OS and 300 GB is consumed by parity information, which equates to 33.3 percent of the available space. Similarly, in a five-disk RAID-5 set of 300 GB disks, approximately 1200 GB 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 300 GB disk will really be only about 279 GB of space. This is because vendors define a gigabyte as one billion bytes, but the OS defines it as 2³⁰ (1,073,741,824) bytes. Also remember that file systems and volume managers have overhead as well.

Note:
Software RAID is a nice option for a small company, but hardware RAID is definitely a better option if the money is available.

Table below breaks down the various aspects of the supported RAID types in Window Server 2012.

Table Supported RAID-level properties on Windows Server 2012


RAID 	RAID	     Fault	Advantages          Minimum      Maximum
Level	Type	     Tolerant	Number of           Number of
	 				            Disk Disk
0	Disk 	     No	  	Fast read	    2		 32
	stripping		and write

1	Disk         Yes	Data redundancy	    2		 2
	mirroring		and faster write
				than RAID-5

5	Disk         Yes	Data redundancy	    3		 32
	stripping		with less overhead
	parity			and faster reads
				than RAID-1

Creating RAID Sets

Now that you understand the concepts of RAID and how to use it, we can look at the creation of RAID sets in Windows Server 2012. The process of creating a RAID set is the same as the process for creating a simple or spanned volume set except for the minimum disk requirements associated with each RAID type.

Creating a mirrored volume set is basically the same as creating a volume set, except that you will select New Mirrored Volume. It is after the disk select wizard appears that you'll begin to see the difference. Since a new mirrored volume is being created, the volume requires two disks.

During the disk select process, if only one disk is selected, the Next button will be unavailable because the disk minimum has not been met. The Select Disks page of the New Mirrored Volume Wizard during the creation of a new mirrored volume, and notice that the Next button is not available.

To complete the process, you must select a second disk by highlighting the appropriate disk and adding it to the volume set. Once the second disk has been added, the Add button becomes unavailable and the Next button is available to complete the mirrored volume set creation.

After you click Next, the creation of the mirrored volume set is again. A drive letter will have to be assigned, and the volume will need to be formatted. The new mirrored volume set will appear in Disk Management. Notice that the capacity of the volume equals one disk even though two have been selected.

To create a RAID-5 volume set, you use the same process that you use to create a mirrored volume set. The only difference is that a RAID-5 volume set requires that a minimum of three disks be selected to complete the volume creation. The process is simple: Select New RAID-5 Volume, and then select the three disks that will be used in the volume set. Assign a drive letter, and format the volume.

Mount Points

With the ever-increasing demands of storage, mount points are used to surpass the limitation of 26 drive letters and to join two volumes into a folder on a separate physical disk drive. A mount point allows you to configure a volume to be accessed from a folder on another existing disk.

Through Disk Management, a mount point folder can be assigned to a drive instead of using a drive letter, and it can be used on basic or dynamic volumes that are formatted with NTFS. However, mount point folders can be created only on empty folders within a volume. Additionally, mount point folder paths cannot be modified; they can only be removed once they have been created. Shows the steps to create a mount point.

Creating Mount Points

Open Server Manager.
Click and then expand Storage.
Select Disk Management.
Right-click the volume where the mount point folder will be assigned and select Change Drive Letter And Paths.
Click Add.
Either type the path to an empty folder on an NTFS volume, or click Browse to select or make a new folder for the mount point.

When you explore the drive, you'll see the new folder created. Notice that the icon indicates that it is a mount point.

Microsoft MPIO

Multipath I/O (MPIO) is associated with high availability because a computer will be able to use a solution with redundant physical paths connected to a storage device. Thus, if one path fails, an application will continue to run because it can access the data across the other path.

The MPIO software provides the functionality needed for the computer to take advantage of the redundant storage paths. MPIO solutions can also load-balance data traffic across both paths to the storage device, virtually eliminating bandwidth bottlenecks to the computer. What allows MPIO to provide this functionality is the new native Microsoft Device Specific Module (Microsoft DSM). The Microsoft DSM is a driver that communicates with storage devices-iSCSI, Fibre Channel, or SAS-and it provides the chosen load-balancing policies. Windows Server 2012 supports the following load-balancing policies:

Failover:
In a failover configuration, there is no load balancing. There is a primary path that is established for all requests and subsequent standby paths. If the primary path fails, one of the standby paths will be used.
Failback:
This is similar to failover in that it has primary and standby paths. However, with failback you designate a preferred path that will handle all process requests until it fails, after which the standby path will become active until the primary reestablishes a connection and automatically regains control.
Round Robin:
In a round-robin configuration, all available paths will be active and will be used to distribute I/O in a balanced round-robin fashion.
Round Robin with a Subset of Paths:
In this configuration, a specific set of paths will be designated as a primary set and another as standby paths. All I/O will use the primary set of paths in a round-robin fashion until all of the sets fail. Only at this time will the standby paths become active.
Dynamic Least Queue Depth:
In a dynamic least queue depth configuration, I/O will route to the path with the least number of outstanding requests.
Weighted Path:
In a weighted path configuration, paths are assigned a numbered weight. I/O requests will use the path with the least weight-the higher the number, the lower the priority.

The process of installing the Microsoft MPIO feature for Windows Server 2012.

Installing Microsoft MPIO

Choose Server Manager by clicking the Server Manager icon on the Taskbar.
Click number 2, Add Roles And Features.
Choose role-based or feature-based installation and click next.
Choose your server and click Next.
Click Next at the Roles screen.
At the Select Features screen, choose the Multipath I/O checkbox. Click Next.
On the Confirm Installation Selections page, verify that Multipath I/O is the feature that will be installed. Click Install.
After the installation completes, the Installation Results page appears stating that the server must be rebooted to finish the installation process.
Click Close.
Restart the system.

Typically, most storage arrays work with the Microsoft DSM. However, some hardware vendors require DSM software that is specific to their products. Third-party DSM software is installed through the MPIO utility as follows:

Open Administrative Tools → MPIO.
Select the DSM Install tab.
Add the path of the INF file and click Install.

iSCSI

Internet Small Computer System Interface (iSCSI) is an interconnect protocol used to establish and manage a connection between a computer (initiator) and a storage device (target). It does this by using a connection through TCP port 3260, which allows it to be used over a LAN, a WAN, or the Internet. Each initiator is identified by its iSCSI Qualified Name (iqn), and it is used to establish its connection to an iSCSI target.

iSCSI was developed to allow block-level access to a storage device over a network. This is different than using a network attached storage (NAS) device that connects through the use of Common Internet File System (CIFS) or Network File System (NFS).

Block-level access is important to many applications that require direct access to storage. MS-Exchange and MS-SQL are examples of applications that require direct access to storage.

By being able to leverage the existing network infrastructure, iSCSI was also developed as an alternative to Fibre Channel storage by alleviating the additional hardware costs associated with a Fibre Channel storage solution.

iSCSI also has another advantage over Fibre Channel in that it can provide security for the storage devices. iSCSI can use Challenge Handshake Authentication Protocol (CHAP or MS-CHAP) for authentication and Internet Protocol Security (IPsec) for encryption. Windows Server 2012 is able to connect an iSCSI storage device out of the box with no additional software needing to be installed. This is because the Microsoft iSCSI initiator is built into the operating system.

Windows Server 2012 supports two different ways to initiate an iSCSI session:

Through the native Microsoft iSCSI software initiator that resides on Windows Server 2012
Using a hardware iSCSI host bus adapter (HBA) that is installed in the computer

Both the Microsoft iSCSI software initiator and iSCSI HBA present an iSCSI Qualified Name that identifies the host initiator. When the Microsoft iSCSI software initiator is used, the CPU utilization may be as much as 30 percent higher than on a computer with a hardware iSCSI HBA. This is because all of the iSCSI process requests are handled within the operating system. Using a hardware iSCSI HBA, process requests can be offloaded to the adapter, thus freeing the CPU overhead associated with the Microsoft iSCSI software initiator. However, iSCSI HBAs can be expensive, whereas the Microsoft iSCSI software initiator is free.

It is worthwhile to install the Microsoft iSCSI software initiator and perform load testing to see how much overhead the computer will have prior to purchasing an iSCSI HBA or HBAs, depending on the redundancy level. Here we explains how to install and configure an iSCSI connection.

Configuring iSCSI Storage Connection

Click the Windows Key → Administrative Tools → iSCSI Initiator.
If a dialog box appears, click Yes to start the service.
Click the Discovery tab.
In the Target Portals portion of the page, click Discover Portal.
Enter the IP address of the target portal and click OK.
The IP address of the target portal appears in the Target Portals box.
Click OK.

To use the storage that has now been presented to the server, you must create a volume on it and format the space.