Disk Management

Disk Management Storage Types Windows 2000 supports the following two types of disk storage: basic storage and dynamic storage. A physical disk must be either basic or dynamic; you can't use both storage types on one disk. You can, however, use both types of disk storage in a multidisk system. Basic Storage The traditional industry standard is basic storage. It dictates the division of a hard disk into partitions (see Figure 6.1). A partition is a portion of the disk that functions as a physically separate unit of storage. Windows 2000 recognizes primary and extended partitions. A disk that is initialized for basic storage is called a basic disk. A basic disk can contain primary partitions, extended partitions, and logical drives. New disks added to a computer running Windows 2000 are basic disks.

Because basic storage is the traditional industry standard, all versions of Microsoft Windows, MSDOS, Windows NT, and Windows 2000 support basic storage. For Windows 2000, basic storage is the default, so all dis ks are basic disks until you convert them to dynamic storage. Dynamic Storage Only Windows 2000 supports dynamic storage, which is a standard that creates a single partition that includes the entire disk. A disk that you initialize for dynamic storage is a dynamic disk. You divide dynamic disks into volumes, which can consist of a portion, or portions, of one or more physical disks. On a dynamic disk, you can create simple volumes, spanned volumes, and striped volumes, as described later in this chapter. Yo u create a dynamic disk by upgrading a basic disk. Dynamic storage doesn't have the restrictions of basic storage; for example, you can size and resize a dynamic disk without restarting Windows 2000. Removable storage devices contain primary partitions only. You can't create extended partitions, logical drives, or dynamic volumes on removable storage devices. You can't mark a primary partition on a removable storage device as active. Partition Types (Basic Disks) You can divide a basic disk into primary and extended partitions. Partitions function as physically separate storage units. This allows you to separate different types of information, such as user data on one partition and applications on another. A basic disk can contain up to four primary partitions, or up to three primary partitions and one extended partition, for a maximum of four partitions. Only one partition can be an extended partition

Primary Partitions Windows 2000 can use the parts of a disk called primary partitions to start the computer. Only a primary partition can be marked as the active partition. The active partition is where the hardware looks for the boot files to start the operating system. Only one partition on a single hard disk can be active at a time. Multiple primary partitions allow you to isolate different operating systems or types of data. To dual boot Windows 2000 with Microsoft Windows 95 or MS-DOS, the active partition must be formatted as FAT because Windows 95 can't read a partition formatted as FAT32 or NTFS. To dual boot with Microsoft Windows 95 OSR2 (a later release of Windows 95 that contained enhancements to Windows 95, such as the ability to read partitions formatted with FAT32) or Windows 98, the active partition must be formatted as FAT or FAT32. Extended Partitions An extended partition is created from free space. There can be only one extended partition on a hard disk, so you should include all remaining free space in the extended partition. Unlike primary partitions, you don't format extended partitions or assign drive letters to them. You divide extended partitions into segments. Each segment is a logical drive. You assign a drive letter to each logical drive and format it with a file system. The Windows 2000 system partition is the active partition that contains the hardwarespecific files required to load the operating system. The Windows 2000 boot partition is the primary partition or logical drive where the operating system files are installed. The boot partition and the system partition can be the same partition. However, the system partition must be on the active partition, typically drive C, while the boot partition could be on another primary partition or on an extended partition. Volume Types (Dynamic Disks) You can convert basic disks to dynamic storage and then create Windows 2000 volumes. Consider which volume type best suits your needs for efficient use of disk space and performance. • •

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• A simple volume contains disk space from a single disk and is not fault tolerant. A spanned volume includes disk space from multiple disks (up to 32). Windows 2000 writes data to a spanned volume on the first disk, completely filling the space, and continues in this manner through each disk that you include in the spanned volume. A spanned volume is not fault tolerant. If any disk in a spanned volume fails, the data in the entire volume is lost. A striped volume combines areas of free space from multiple hard disks, up to 32, into one logical volume. In a striped volume, Windows 2000 optimizes performance by adding data to

all disks at the same rate. If a disk in a striped volume fails, the data in the entire volume is lost.

The Windows 2000 Server products provide fault tolerance on dynamic disks. Fault tolerance is the ability of a computer or operating system to respond to a catastrophic event without loss of data. The Windows 2000 Server products provide mirrored volumes and RAID-5 volumes that are fault tolerant. Windows 2000 Professional does not provide fault tolerance. Creating multiple partitions or volumes on a single hard disk allows you to efficiently organize data for tasks such as backing up. For example, partition one-third of a hard disk for the operating system, onethird for applications, and one-third for data. Then, when you back up your data, you can back up the entire partition instead of just a specific folder. File Systems Windows 2000 supports the NTFS, FAT, and FAT32 file systems. Use NTFS when you require a partition to have file- and folder-level security, disk compression, disk quotas, or encryption. Only Windows 2000 and Windows NT can access data on a local hard disk that is formatted as NTFS. If you plan to promote a server to a domain controller, format the installation partition with NTFS. FAT and FAT32 allow access by, and compatibility with, other operating systems. To dual boot Windows 2000 and another operating system, format the system partition with either FAT or FAT32. FAT and FAT32 don't offer many of the features that NTFS supports, for example, file -level security. Therefore, in most situations, you should format the hard disk with NTFS. The only reason to use FAT or FAT32 is for dual booting. If you have a volume that is formatted with FAT or FAT32, Windows 2000 provides the Convert command to allow you to convert it from FAT or FAT32 to NTFS without having to reformat your volume. To do this you enter the following command in a Command Prompt window: Convert volume /FS:NTFS /V Note that volume is replaced by the drive letter followed by a colon. The /V indicates the command should be run in verbose mode. For example, if you wanted to convert drive C from FAT to NTFS you would type the following command: Convert C: /FS:NTFS /V

Management Tasks

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• Working with simple volumes Working with spanned volumes Working with striped volumes Adding disks Changing storage types Viewing and updating information Managing disks on a remote computer

Working with Simple Volumes

A simple volume contains disk space from a single disk. You can extend a simple volume to include unallocated space on the same disk. You can create a simple volume and format it with NTFS, FAT, or FAT32. You can extend a simple volume only if it is formatted with NTFS. You can create a simple volume by following these steps: 1. 2. 3. 4.

1. Select Disk Management in the Storage section of the Computer Management snap-in. On the dynamic disk where you want to create the volume, right-click the unallocated space, and then click Create Volume. This launches the Create Volume wizard. In the Create Volume wizard, click Next. Click Simple Volume, and then follow the instructions on your screen.

Spanned Volumes A spanned volume consists of disk space from multiple disks; spanned volumes enable you to use the total available free space on multiple disks more effectively. You can create spanned volumes only on dynamic disks, and you need at least two dynamic disks to create a spanned volume. Spanned volumes can't be part of a striped volume and are not fault tolerant. Figure 6.4 introduces some of the important concepts for combining free space to create spanned volumes, to extend spanned volumes, and to delete spanned volumes. Combining Free Space to Create a Spanned Volume You create spanned volumes by combining various-sized areas of free space from 2 to 32 disks into one large logical volume. The areas of free space that comprise a spanned volume can be different sizes. Windows 2000 organizes spanned volumes so that data is stored in the space on one disk until it is full, and then, starting at the beginning of the next disk, data is stored in the space on the second disk. Windows 2000 continues this process in the same way on each subsequent disk up to a maximum of 32 disks. By deleting smaller volumes and combining them into one spanned volume, you can free drive letters for other uses and create a large volume for file system use. Extending and Deleting Spanned Volumes You can extend existing spanned volumes formatted with NTFS by adding free space. Disk Management formats the new area without affecting any existing files on the original volume. You can't extend volumes formatted with FAT or FAT32.

You can extend spanned volumes on dynamic dis ks onto a maximum of 32 dynamic disks. After a volume is extended onto multiple disks (spanned), it can't be part of a striped volume. After a spanned volume is extended, no portion of it can be deleted without deleting the entire spanned volume. You can't extend a system volume or a boot volume.

Working with Striped Volumes Striped volumes offer the best performance of all the Windows 2000 disk management strategies. In a striped volume, data is written evenly across all physical disks in 64-KB units, as shown in. Because all the hard disks that belong to the striped volume perform the same functions as a single hard disk, Windows 2000 can issue and process concurrent I/O commands simultaneously on all hard disks. In this way, striped volumes can increase the speed of system I/O. You create striped volumes by combining areas of free space from multiple disks (from 2 to 32) into one logical volume. With a striped volume, Windows 2000 writes data to multiple disks, similar to spanned volumes. However, on a striped volume, Windows 2000 writes files across all disks so that data is added to all disks at the same rate. Like spanned volumes, striped volumes don't provide fault tolerance. If a disk in a striped volume fails, the data in the entire volume is lost. You need at least two dynamic disks to create a striped volume. You can create a striped volume onto a maximum of 32 disks. You can't extend striped volumes. You can create a striped volume by doing the following: 1.

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1. In Disk Management, on the dynamic disk where you want to create the striped volume, right-click the unallocated space, and then click Create Volume. This launches the Create Volume wizard. In the Create Volume wizard, click Next, click Striped Volume, and then follow the instructions on your screen.

Adding New Disks To add a new disk, install or attach the new physical disk (or disks), and then click Rescan Disks on the Action menu of the Disk Management snap-in. You must use Rescan Disks every time you remove or add disks to a computer. You shouldn't need to restart the computer when you add a new disk to your computer. However, you might need to restart the computer if Disk Management doesn't detect the new disk after you run Rescan Disks.

Adding Disks That You Removed from Another Computer If you want to uninstall or remove a disk from one computer and then install the disk in a different computer, the process is different. You can add a disk that has been removed from another computer by doing the following: 1. 2.

Open Disk Management. Disk Management displays the new disk labeled as Foreign. Right-click the new disk, and then click Import Foreign Disk. A wizard provides on-screen instructions.

Changing Storage Type You can upgrade a disk from basic storage to dynamic storage at any time, with no loss of data. When you upgrade a basic disk to a dynamic disk, any existing partitions on the basic disk become simple volumes. Any existing striped or spanned volume sets created with Windows NT 4 become dynamic striped or spanned volumes, respectively. Any disks to be upgraded must contain at least 1 MB of unallocated space for the upgrade to succeed. Before you upgrade disks, close any programs that are running on those disks. Upgrading Basic Disks to Dynamic Disks To upgrade a basic disk to a dynamic disk, in the Disk Management snap-in, right-click the basic disk that you want to upgrade, and then click Upgrade To Dynamic Disk. A wizard provides on-screen instructions. The upgrade process requires that you restart your computer. After you upgrade a basic disk to a dynamic disk, you can create volumes with improved capabilities on the disk. After you upgrade a disk to dynamic storage, it can't contain partitions or logical drives. Only Windows 2000 can access dynamic disks. If you are dual booting with another operating system, for example, Windows 95 or Windows 98 loaded on drive C, these operating systems will no longer run. Only Windows 2000 can access a dynamic drive.

Hard Drive Technologies Directly Attached Storage (DAS) These are traditional hard disks, which uses one of two technologies to interface to the motherboard: parallel ATA interface. SCSI (SCSI) from Adaptec and LSI logic FC (Fiber Channel) such as IBM FastT900 storage array But Fibre Channel was designed as a campuswide network, not to exceed 100 miles, and there are many difficult barriers to transporting Fibre Channel over the WAN because of Fibre Channel's sensitivity to delay. Additionally, while there are established protocols such as IFCP (Internet Fibre Channel Protocol) and FCoIP Fibre Channel over IP) to allow Fibre Channel to extend further, Fibre Channel is a closed network and these alternatives are piecemeal approaches that require specialized hardware and introduce additional complexities and vulnerabilities into the network. To speed things up with ATA: SCSI provides significant performance gains for drives or controllers because it has a robust tagged command queuing implementation which allows multiple commands to be outstanding and executed in an optimal execution manner.

This intelligence makes SCSI more expensive, since SCSI uses two processors — one for executing the commands and handling the interface and another processor controlling the head positioning through servos. Ultra320 SCSI PCI Express replaces PCI and PCI-X on motherboards, and as a serial interconnect, provides high performance (multiple Gbps per connection) and scalability to networked storage systems. SATA (Serial ATA) also known as IDE was defined by the Serial ATA International Organization (SATA-IO) to be software compatible with Parallel ATA. It uses ATA disks in a redundant array to provide mass, reliable storage inexpensively. It has a max. data transfer rate of 59 MBps through a single port. Serial ATA supports data rates up to 150 MB/s, versus the embraved industry standard of 100 MB/s for Parallel ATA. The new interface also provides for command queuing to further boost system performance. SATA uses smaller cable connectors with improved silicon design for lower voltage that alleviates current design requirements in Parallel ATA from Seagate SAS (Serial Attached SCSI) began shipping in 2005 as Seagate and Maxtor Atlas 10K V and Atlas 15K II drives. SAS offers a serial point-to-point technology which achieves 3Gb/s because it eliminates the parallel bus overhead of today's parallel SCSI technology. SAS also adds dual porting , full duplex, device addressing up to 128 drives. Low-cost switches, known as expanders, aggregate hundreds of drives. yet SAS offers longer cable distances. The SAS interface is compatible with (provides universal interconnect with) SATA devices and logical SCSI compatibility, but when an SAS system is used as a base. However, SAS connectors are much smaller than SCSI connectors.

DAS vs. NAS-SAN Adapted from an Aberdeen Group report and Intel Adapted from this article: Scalability: DAS storage arrays have limited capacity and are difficult to grow. SAN can dynamically allocate storage as required and have larger capacity limits (64 TBs for a FastT900 storage array) Utilization: Since individual drives are 30% used, SANs make more free space available by combining small amounts of storage capacity together. SAN enable data mirroring across multiple sites — a key feature in business continuity plans for priority one services. SAN provides snapshot technology for data replication and protection large volumes of SAN storage can be managed more easily that manage 50TBs of direct attached storage and do so proactively rather than reactively when problems occur. iSCSI (Internet SCSI) The iSCSI (Internet SCSI) RFC 2026 at draft 20 completed in February 2003 specifies how to run SCSI commands over TCP/IP, providing a lower cost alternative for storage area networking, using cards from:

QLogic SANblade[tm] 4000 Series Intel PRO/1000 T IP Storage Adapter Emulex GN9000/SI(VI) 1Gb/s iSCSI Host Bus Adapters Adaptec ASA-7211 iSCSI HBA iSCSI IETF RFC 3720 introduces complete error recovery mechanisms called Error Recovery Level Two (ERL 2) In any SCSI connection there is at least one initiator and one target. Initiators are the devices which request, or initiate, any SCSI communications. They request data writes, reads and any other SCSI operations. Usually initiator is the HBA in the computer which is using SCSI disks, tapes and other target devices. Targets are the devices which perform SCSI commands at a request from initiators, but never initiate SCSI activity. Examples of SCSI targets are: disks, tapes, RAID arrays, robotic libraries and many more. A Performance Comparison of NFS and iSCSI for IP-Networked Storage showed that iSCSI is faster than NFS because iSCSI caches and updates meta-data asynchronously and transfers blocks rather than files. here and Mathias Gug of CERNMicrosoft iSCSI Software Initiator Version 2.0 (build 1653)

Network Attached Storage (NAS) NAS filers are special-purpose file servers (i.e., "appliances") that attach to a local area network (LAN) to deliver files to client systems - or other servers acting as clients - via the LAN. NAS files can be shared by client systems running different operating systems (Windows and Linux, for example). A NAS filer lets clients share files, but does not share its storage with other servers. Most NAS supports Multi-platform File Sharing by simultaneously supporting Windows Common Internet File System (CIFS) and Unix Network File System (NFS) as well as file systems associated with Macintosh, Novell, and other operating systems. Some NAS systems can expand into multiple terabytes, but non-scaling NAS system need to be taken offline to redistribute data when adding capacity.

Storage Area Network (SAN) Storage A SAN provides a high-speed data path between server and storage independent of the LAN. SAN storage connects to multiple servers through a separate fabric (storage area network), not via the LAN. Servers access the files contained in SAN storage using basic block I/O commands - just as if the storage were part of the server - not by calling for files. However, although a SAN does not (usually) offer file sharing, it does offer storage sharing to servers. The storage sharing can be physical (with a fixed logical "wall" between servers that run different operating systems), or partitioned logical storage (shared by servers that run the same operating system). SAN solutions can outperform NAS when large amounts of data need to be moved or accessed (e.g., for backup or streaming applications). Converged NAS/SAN products are "two dialect device," or 2DD for short. BlueArc offers a high-end NAS server with some SAN attributes, such as support for 10,000 or more users, multi-gigabit throughput, and up to 250 TB capacity.