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Managing Storage Lesson 3 Objectives Storage • While you need sufficient processing power and a sufficient amount of RAM, you will also most likely need a large amount of storage. • Although simple servers usually require that you install Windows Server on a local IDE (parallel and serial) or SCSI hard drive, more complex systems may use a form of RAID or attached remote computer storage devices such as a storage area network (SAN) or network attached storage (NAS). RAID • Because most drives are half-electronic and half- mechanical devices, you can connect multiple drives to special controllers to provide data production, system reliability, and better performance. • A redundant array of independent disks (RAID) uses two or more drives in combination to create a fault- tolerant system that protects against physical hard drive failure and increases hard drive performance. • A RAID can be accomplished with either hardware or software and is usually used with network servers. RAID 0 • RAID 0 stripes data across all drives. • With striping, all available hard drives are combined into a single large virtual file system, with the file system’s blocks arrayed so that they are spread evenly across all the drives. • Unfortunately, with RAID 0, there is no parity control or fault tolerance; therefore, it is not a true form of RAID. • However, RAID 0 does have several advantages because it offers increased performance through load balancing. RAID 1 • RAID 1 is sometimes known as disk mirroring. • Disk mirroring copies a disk or partition onto a second hard drive. Specifically, as information is written, it is written to both hard drives simultaneously. • If one of the hard drives fails, the PC will still function because it can access the other hard drive. – Then, should you later replace the failed drive, data will be copied from the remaining good drive to the new drive. RAID 5 • RAID 5, which is similar to striping, except the space equivalent to one of the hard drives is used for parity (error correction) to provide fault tolerance. • To increase performance, the error correction function is spread across all hard drives in the array to avoid having one drive doing all the work in calculating the parity bits. • Therefore if one drive fails, you can still continue working because parity calculations with the remaining drives will fill in any missing data. • Later, when the failed drive is replaced, the missing information will be rebuilt. Hybrid RAID • There are two other forms of RAID worth mentioning, both of which are considered hybrid or nested RAIDs: – RAID 1+0 is a mirrored dataset (RAID 1), which is then striped (RAID 0). – RAID 0+1 is a striped dataset (RAID 0), which is then mirrored (RAID 1). Hot Spare • A hot spare is much like it sounds. When drives need to be fault tolerant, you can combine a hot spare drive with a RAID. • Then, if a drive fails, the system will automatically grab the hot spare drive to replace the failed drive and rebuild or restore the missing data. Network Attached Storage • Network attached storage (NAS) is a file-level data storage device that is connected to a computer network to provide shared drives or folders, usually using SMB/CIFS. • NAS devices usually contain multiple drives in a form of RAID for fault tolerance and are managed usually using a web interface. Storage Area Network • A storage area network (SAN) is an architecture used for disk arrays, tape libraries, and optical jukeboxes to appear as locally attached drives on a server. • A SAN always uses some form of RAID and other technology to make the system redundant against drive failure and to offer high performance. • SANs also usually contain spare drives. • To provide a high level of data throughput, SANs use the SCSI protocol and either iSCSI or Fibre Channel interface. Host Bus Adapter • A host adapter, sometimes referred to as host bus adapter (HBA), connects a host system such as a computer to a network or storage device. • It is primarily used to refer to connecting SCSI, Fibre Channel, and eSATA devices LUNs • Logical unit numbers (usually referred to as LUNs) allow a SAN to break its storage down into manageable pieces, which are then assigned to one or more servers in the SAN. • It is a logical reference that can comprise a disk, a section of a disk, a whole disk array, or a section of a disk array. • LUNs serve as logical identifiers through which you can assign access and control privileges. Fibre Channel • Optic fiber cabling offers higher bandwidths and can be used over longer distances than copper cabling because signals travel with less loss and are immune to electromagnetic interference. • Fibre Channel or FC is a gigabit-speed technology primarily used for storage networking. • It uses a Fibre Channel Protocol (FCP) as its transport protocol, which allows SCSI commands to be issued over Fibre Channel. iSCSI • Internet Small Computing System Interface or iSCSI is an Internet Protocol (IP)-based storage networking standard for linking data storage facilities. • iSCSI allows clients to send SCSI commands over a TCP/IP network using TCP port 3260. • Similar to Fibre Channel, iSCSI can communicate using Gigabit Ethernet or Fibre, and it can connect a SAN to multiple servers over a distance. • Although iSCSI uses normal network technology to communicate, the network adaptor must be dedicated to iSCSI. iSCSI Initiator Software Storage Explorer • Windows Server 2008 includes Storage Explorer and Storage Manager for SANs to manage Fibre Channel, iSCSI fabrics, and LUNs. • Storage Explorer allows you to view and manage the Fibre Channel and iSCSI fabrics that are available in your SAN. • Storage Explorer can display detailed information about servers connected to the SAN, as well as components in the fabrics such as host bus adapters (HBAs), Fibre Channel switches, and iSCSI initiators and targets. Storage Explorer Disk Structure • Before you use a disk, you must prepare the disk for usage by creating partitions or volumes and formatting the disk. • When you want to use a disk in Windows, you have several choices to make: – Disk partitioning style – Disk type – Type of volume – File system Partitioning • Partitioning is defining and dividing a physical or virtual disk into logical volumes called partitions. • Each partition functions as if it were a separate disk drive, which can be assigned a drive letter. • To keep track of how a disk is divided, the disk uses a partition table. • Formatting a disk prepares the volume’s file system by creating a file allocation table to keep track of the files and folders on the volume. Partitioning Style • Partitioning style refers to the method that Windows uses to organize partitions on a disk. • Windows Server 2008 supports two types of disk partitioning styles: – Master Boot Record (MBR) – GUID Partition Table (GPT) Windows Hard Disk Storage • Most versions of Windows servers—including Windows Server 2008—support two types of hard disk storage – Basic disks are the traditional disk type, – Dynamic disks offer software-based RAID and the ability to resize volumes without rebooting. Dynamic Disks • Dynamic disks support five types of volumes: – Simple volume – Spanned volume – Striped volume – Mirrored volume – RAID-5 volume File System • A file system is a method of storing and organizing computer files and the data they contain to make it easy to find and access this information. • A file system also maintains the physical location of the files so that you can find and access the files in the future. • Windows Server 2008 supports FAT16, FAT32, and NTFS file systems on hard drives. FAT16 and FAT32 • FAT16, sometimes referred to generically as File Allocation Table (FAT), is a simple file system that uses minimum memory and was even used with DOS. – Unfortunately, FAT can only support volumes up to 2 GB. • FAT32 was released with the second major release of Windows 95. Although this file system can support larger drives, today’s Windows versions support volumes only up to 32 GB. NTFS File System • As mentioned earlier, New Technology File System (NTFS) is the preferred file system, largely because it supports both a much larger hard disk (up to 16 exabytes) and long file names. • NTFS is more fault tolerant than previous file systems used in Windows because it uses journaling to make sure that disk transactions are written properly before they can be recognized. • NTFS offers better security through permissions and encryption. Disk Management • The main disk management tool in Windows Server 2008 is the MMC snap-in called Disk Management, which is also part of the Computer and Management consoles. • In addition, you can use a diskpart.exe and the Format command to partition and format a drive, as well as Windows Explorer to format a drive. Disk Management Initializing a Disk Converting to a Dynamic Disk Creating a Simple Volume Assigning Drive Letter or Path Formatting Drive Extending Volume Summary • Today’s drives are either IDE drives (mostly found on consumer computers) or SCSI drives (mostly found in servers). • A redundant array of independent disks (RAID) uses two or more drives in combination to create a fault-tolerant system that protects against physical hard drive failure and increase hard drive performance. Summary • Network attached storage (NAS) is a file-level data storage device that is connected to a computer network to provide shared drives or folders, usually using SMB. • A storage area network (SAN) is an architecture used for disk arrays, tape libraries, and optical jukeboxes to appear as locally attached drives on a server. • A host adapter, sometimes referred to as host bus adapter (HBA), connects a host system such as a computer to a network or storage devices. Summary • A file system is a method of storing and organizing computer files and the data they contain to make it easy to find and access this information. A file system also maintains the physical location of the files so you can find and access the files in the future. • Currently, NTFS is the preferred file system, in part because it supports much larger hard disks (up to 16 exabytes) and long filenames. • NTFS is a journaling file system that makes sure a disk transaction is written properly before it is recognized. • NTFS offers better security through permissions and encryption.
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