The partition where the computer starts up. The active partition must be a primary partition on a basic disk. If you use Microsoft® Windows NT® or Window® 2000 exclusively, the active partition can be the same as the system partition. If you have a dual-boot system with two operating systems (such as Windows 2000 and Windows NT OR Windows NT and Windows 98® or MS-DOS®) the active partition must contain the startup files for both operating systems. See also Basic disk, Extended partition, Extended partition, Partition, Primary partition.
An array group provides a mechanism to group disks that are controlled by a particular RAID controller. You can create virtual disks from disks in an array group if you have a SCSI RAID controller. However, with the PowerVault™ 660F controller, you will need to further define the array group into one or more disk groups before creating virtual disks. See also Disk groups.
Breaking a mirror creates two simple volumes with individual drive letters. Each volume contains the data on the mirror at the time the mirror was broken. The data is no longer redundant, but it remains intact. Compare with Removing a mirror.
The volume, formatted for either an NTFS or FAT file system, that contains the Windows NT/2000 operating system and its support files. The boot volume can be the same as the system volume. See also FAT and FAT32, NTFS, System volume, and Volume.
A fast storage area that keeps a copy of data or instructions for quicker data retrieval. Storage cache usually resides on RAID controllers and boosts performance because the CPU doesn't have to wait for a disk head to spin. Data can be written and read directly from cache.
Controller-controller nexus. A controller-controller nexus refers to the state in which both redundant controllers are in communication with each other. In this state, each controller can copy write-back data to its partner controller and can determine whether the other controller is operating.
Clustering is the process of associating multiple servers so that they function as a single, virtual server. Clustering can provide greater overall system availability, performance, and capacity for the server platforms.
A consistency check verifies the accuracy of redundant data in a RAID group. For example, on a virtual disk with parity, checking consistency computes the parity of the data drives and compares the results with the contents of the parity drives.
This is a factory-installed, bootable partition on the hard-disk drive that provides utilities and diagnostics for your Dell hardware and software. When activated, the partition boots and provides an executable environment for the partition's utilities.
A Fibre Channel hardware configuration in which the host bus adapter(s) of a single server are directly connected to Fibre Channel RAID controller(s). This attachment method uses point-to-point Fibre Channel connectivity. In this configuration, the Fibre Channel RAID controller storage is confined to that server and is not shared across multiple servers. See also Redundant controllers.
With redundant Fibre Disk RAID controllers that support a large number of physical disks, it is necessary to define one or more disk groups from the array group before creating virtual disks. You then create virtual disks from a disk group rather than from the larger array group. See also Array group.
Disk striping writes data across multiple disk drives instead of just one disk. Disk striping involves partitioning each drive storage space into stripes that can vary in size. These stripes are interleaved in a repeated, sequential manner. The combined storage space is composed of stripes from each drive.
A logical disk that is managed by Array Manager software. Dynamic disks can contain only dynamic volumes (that is, volumes created with Array Manager software). Dynamic disks cannot contain partitions or logical drives, nor can they be accessed by MS-DOS or Windows 95®/98. See also Dynamic volume, Partition.
A logical volume that is created with Array Manager software. Dynamic volumes include simple, spanned, striped, mirrored, and RAID-5. You must create dynamic volumes on dynamic disks. See also Dynamic disk, Volume.
The process of upgrading partitions and Windows NT 4.0 Disk Administrator RAID volumes to dynamic volumes by upgrading the disk(s) they are on to dynamic. See the section Upgrade Disks with Legacy Volumes to Dynamic in the Volume Management chapter for details.
A portion of a basic disk that can contain logical drives. Use an extended partition if you want to have more than four volumes on your basic disk. Only one of the four partitions allowed per physical disk can be an extended partition, and no primary partition needs to be present to create an extended partition. Extended partitions can be created only on basic disks. See also Basic disk, Logical drive, Partition, Primary partition, Active partition.
Failback is a feature of RAID in which a RAID controller operating in failover mode detects the presence of a second operating controller, exits failover mode, and resumes its normal mode of operation. For more information, see Failover and Failback in the Storage Management Concepts chapter.
Failover is a feature of RAID in which a pair of RAID controllers that are in communication with one another simultaneously process the same input/output commands to an array of disks. If one of the controllers fails, the surviving controller detects the failure and automatically assumes the function of the failed controller. For more information, see Failover and Failback in the Storage Management Concepts chapter.
FAT and FAT32 are file systems that are defined as follows:
FAT (File Allocation Table) — A file system used by MS-DOS, Windows 3.x, Windows 95, and Windows 98. Windows NT and Windows 2000 also can use the FAT file system. The operating system maintains a table to keep track of the status of various segments of disk space used for file storage.
FAT32 (File Allocation Table) — A derivative of the file allocation table (FAT) file system. FAT32 supports smaller cluster sizes than FAT, thus providing more efficient space allocation on FAT32 drives. FAT32 is designed for larger disks than FAT.
Software (programs or data) that has been written onto read-only memory (ROM). Firmware can boot and operate a device. Each controller contains firmware which helps provide the controller's functionality.
These are legacy systems that Array Manager can identify. These are basic volumes. You can use Disk Administrator in parallel with Array Manager if you need to keep these disks as basic disks.
Host bus adapter. A PCI adapter card which resides in the server whose only function is to convert data commands from PCI-bus format to storage interconnect format (examples: SCSI, Fiber Channel) and communicate directly with disk drives, tape drives, CD-ROMS, or other storage devices.
A hot spare is an extra, unused disk that is part of a disk subsystem. It is assigned as a backup disk that can take over when a primary disk fails. Hot spares remain in standby mode, ready for activation in case of a disk failure. Hot spares can replace failed drives without interrupting the system or requiring user intervention.
A logical drive is a partition you create within an extended partition on a basic disk. A logical drive can be formatted and assigned a drive letter. Only basic disks can contain logical drives. A logical drive cannot span multiple disks. See also Basic disk, Basic volume, Extended partition.
LS modules are cards installed in slots at the front of the enclosure. Each LS module has an SES processor that monitors environmental functions and a Loop Redundancy Circuit (LRC) function, which maintains the viability of the Fibre Channel loop.
Logical unit number. A LUN is a logical representation of physical storage. You determine whether a LUN is a disk drive, a number of disk drives, or a partition on a disk drive, depending on the RAID configuration.
A fault-tolerant volume that duplicates data on two physical disks. It provides data redundancy by using a copy (mirror) of the volume to duplicate the information contained in the volume. The mirror is located on a different disk. If one of the physical disks fails, the data on the failed disk becomes unavailable, but the system continues to operate using the unaffected disk.
A mirrored volume is slower than a RAID-5 volume in read operations but faster in write operations. You can create mirrored volumes only on dynamic disks. You cannot extend mirrored volumes. In Windows NT 4.0 Disk Administrator, a mirrored volume is known as a mirror set. See also Dynamic disk, Dynamic volume, Fault tolerance, RAID, Volume.
A controller-controller nexus refers to the state in which both redundant controllers are in communication. In this state, each controller can copy write-back data to its partner controller and can determine whether the other controller is operating.
An advanced file system designed for use specifically within the Windows NT operating system. It supports file system recovery, extremely large storage media, long file names, and various features for the POSIX subsystem. It also supports object-oriented applications by treating all files as objects with user-defined and system-defined attributes. NTFS is also called Windows NT file system. See also FAT and FAT32.
The capability of extending an existing simple or spanned dynamic volume while the volume is online. This is done with the Extend Volume command. For more information, see Extending a Dynamic Simple or Spanned Volume in the Volume Management chapter.
Redundant information that is associated with a block of information. In Array Manager software, parity is a calculated value used to reconstruct data after a failure.
RAID-5 volumes stripe data and parity intermittently across a set of disks. Within each stripe, the data on one disk is parity data and the data on the other disks is normal data. RAID-5 volumes therefore require at least three disks to allow for this extra parity information. When a disk fails, Array Manager software uses the parity information in those stripes in conjunction with the data on the good disks to recreate the data on the failed disk. See also Fault tolerance, Volume, Striped volume (RAID-0), RAID-5 volume (stripe set with parity), RAID-10 and RAID-0+1 (striping over mirrored sets).
A portion of a physical disk that functions as though it were a physically separate disk. Partitions can be created only on basic disks. Partitions cannot span disks; they must be a contiguous region. See also Basic disk, Extended partition, Extended partition, Partition, Active partition.
A physical array is a collection of physical disk drives governed by RAID management software. A physical array appears to Array Manager as one or more logical drives.
A volume you create using unallocated space on a basic disk. Microsoft Windows NT and other operating systems can start from a primary partition. You can create up to four primary partitions on a basic disk, or three primary partitions and an extended partition. Primary partitions can be created only on basic disks and cannot be subpartitioned. See also Basic disk, Dynamic volume, Extended partition, Partition.
Providers run on a managed node along with the server on the Microsoft Windows NT 4.0 or Windows 2000 operating system. Providers are plug-ins to the server framework. Each provider is specific to the hardware controller or software component that the provider manages.
Hardware RAID (Redundant Array of Independent Disks) refers to:
An array of multiple independent hard disk drives that, in varying levels, provide high performance and fault tolerance.
The term that describes a method used to standardize and categorize fault-tolerant disk systems.
RAID levels provide various mixes of performance, reliability, and cost. Array Manager supports the available RAID levels of the particular hardware included in your system.
A RAID-5 volume is a fault-tolerant volume with data and parity striped intermittently across three or more physical disks. Parity is a calculated value that is used to reconstruct data after a failure. If a portion of a physical disk fails, you can recreate the data that was on the failed portion from the remaining data and parity. You can create RAID-5 volumes only on dynamic disks. You cannot mirror or extend RAID-5 volumes. In Windows NT 4.0 Disk Administrator, a RAID-5 volume is known as a striped set with parity. See also Fault tolerance, Parity, RAID.
These two RAID levels involve striped data that is mirrored. They provide both speed (from striping) and fault tolerance (from the mirroring). RAID-10 is available with PERC controllers; RAID-0+1 is a feature of the PowerVault 660F controller. See also Fault tolerance, Parity, RAID.
Refers to two identical Fibre Channel RAID controllers that share a common set of array disks. The two controllers can be connected to a server in a direct attach or in a SAN configuration. The two controllers communicate with each other to verify that both are functioning properly through a ping/acknowledgment sequence. Failure to acknowledge the ping triggers failover. When one controller fails, the surviving controller takes over the resources of the failed controller. This failover process is transparent to the applications running on the host. See also Direct Attach.
Removing a mirror from a volume destroys the data from the selected mirror and leaves the other mirror intact. After you remove a mirror, the space on the disk used by the removed mirrored volume becomes unallocated space. The remaining volume becomes a simple volume on the disk. Compare with Breaking a mirror.
Small Computer System Interface. A processor-independent standard for system-level communications between a computer and intelligent devices including hard-drives, floppy disks, CD drives, printers, scanners, and so on.
A volume that consists of contiguous space on a single disk. You can extend a simple volume within the same disk or onto additional disks. If you extend a simple volume across multiple disks or across noncontiguous areas on the same disk, it becomes a spanned volume. You can create simple volumes only on dynamic disks. Simple volumes are not fault tolerant but can be mirrored.
When a basic disk with a partition is upgraded, the partition becomes a simple volume. An extended partition on a basic disk also becomes a simple volume when the disk is upgraded to dynamic. See also Dynamic disk, Dynamic volume, Fault tolerance, Spanned volume.
This is a method of determining the reliability of an array disk by performing a predictive failure analysis on each disk, as defined by that disk's vendor. Array Manager picks up alerts sent from each RAID controller, if the hard disk supports S.M.A.R.T.
Simple NetWork Management Protocol. SNMP, a popular network control and monitoring protocol, is part of the original TCP/IP protocol suite. SNMP provides the format in which vital information about different network devices, such as network servers or routers, can be sent to a management application.
A volume made up of disk space on more than one physical disk. A spanned volume can also consist of two or more noncontiguous areas on a single disk. You can add more space to a spanned volume by extending it at any time. You can create spanned volumes only on dynamic disks. Spanned volumes are not fault tolerant. In Windows NT 4.0 Disk Administrator, a spanned volume is known as a volume set. See also Dynamic disk, Dynamic volume, Fault tolerance, Simple volume.
A volume that stores data in stripes on two or more physical disks. Data in a striped volume is allocated alternately and evenly (in stripes) to the disks of the striped volume. Striped volumes are not fault tolerant, but you can mirror a striped dynamic volume to ensure redundancy. You can also extend a striped dynamic volume. See also Dynamic disk, Dynamic volume, Fault tolerance, Simple volume, RAID.
Abbreviation for Transmission Control Protocol/Internet Protocol. A system for transferring information over a computer network containing dissimilar systems, such as PC and UNIX.
Available disk space that is not allocated to any partition, logical drive, or volume. The type of object you can create on unallocated space depends on the disk type (basic or dynamic). For basic disks, you can use unallocated space outside partitions to create primary or extended partitions. You can use free space inside an extended partition to create a logical drive. For dynamic disks, you can use unallocated space to create dynamic volumes. Unlike with basic disks, you do not select the exact disk region used to create the volume.
A virtual disk is an abstract entity used by Array Manager that allows you to use different hardware RAID layouts on selected array disks. Virtual disks are hardware RAID logical drives. After the virtual disk is created and the system is rebooted, the virtual disk appears as a disk in Windows NT/2000. A virtual disk is functionally identical to a physical disk from the standpoint of applications.
