Storage Foundation 7.4.1 Administrator's Guide - Windows

In Storage Foundation for Windows, the mode in which DMP allocates the data transfer across the possible paths to and from an array, thus enabling load balancing. With this mode, DMP implements a round-robin algorithm, selecting each path in sequence for each successive data transfer to or from a disk. For example, if paths A and B are active, the first disk transfer occurs on path A, the next on path B, and the next on path A again.

The partition or volume from which the computer starts up. On a basic disk, the active partition must be a primary partition. For a dynamic disk, a dynamic volume cannot be marked active directly. However, a basic disk with a system partition can be upgraded to dynamic. After the disk is upgraded and the computer is restarted, the system partition becomes a system volume, which retains its active status.

Upgrading a basic disk with a system partition to a dynamic disk preserves the partition table information, which is required when reinstalling the Windows operating system.

In Storage Foundation for Windows, the mode in which DMP allocates data transfer to and from an array across the preferred path. This path is always active, and the other path or paths act as backups that are called into service if the current operating path fails. This option does not provide load balancing.

The volume that contains the Windows operating system and its support files. The boot volume can be in the same location as the system volume. In Windows, the system partition or volume is the one the computer starts from, while the boot volume is the one that has the operating system and support files.

In Storage Foundation for Windows, the percentage of volume capacity at which an error is reported. The default is 90 percent.

A physical data storage device attached to a computer.

The process of evacuating or moving the entire contents of a healthy disk to the free space on a dynamic disk in the same dynamic disk group.

Storage Foundation for Windows organizes disks into disk groups. Disk groups provide a way of organizing disks in a system and simplifying storage management for systems with large numbers of disks. They also allow disks to be moved between computers to easily transfer the storage between computers.

In Storage Foundation for Windows, the process of replacing a failed disk with an empty basic disk. The volume configuration is recreated on the new disk. The contents of nonredundant volumes are not guaranteed. Redundant volumes will be automatically resynchronized.

The path to a local drive that is mounted at an empty folder on an NTFS volume.

A dynamic disk is a physical disk that can contain dynamic volumes created with Storage Foundation for Windows. A dynamic volume organizes space on one or more physical disks by using a specific type of volume layout. The six types of dynamic volume layouts are simple, spanned, mirrored, striped, RAID-5, and mirrored striped (RAID 0+1). On a dynamic disk, space is organized through volumes rather than partitions. Because a dynamic disk does not have the partitioning scheme used by Windows NT, Windows 95/98, and MS-DOS, dynamic disks cannot be accessed through those operating systems.

In Storage Foundation for Windows, the Dynamic Multipathing option adds fault tolerance to disk storage by making use of multiple paths between a computer and individual disks in an attached disk storage system. Disk transfers that would have failed because of a path failure are automatically rerouted to an alternate path. Dynamic Multipathing also improves performance by allowing load balancing between the multiple paths. Two forms of Dynamic Multipathing are available, DMP and MPIO.

In Storage Foundation for Windows, dynamic volumes are volumes created on dynamic disks in place of partitions. A dynamic volume consists of a portion or portions of one or more physical disks and is organized in one of five volume layout types: concatenated, mirrored, striped, RAID-5, and mirrored striped (RAID 0+1). The size of a dynamic volume can be increased if the volume is formatted with NTFS and there is unallocated space on a dynamic disk within the dynamic disk group onto which the volume can be extended.

A portion of a basic disk that can contain logical drives. An extended partition is used to have more than four volumes on a basic disk. A basic disk can contain up to four primary partitions or three primary partitions plus an extended partition. The extended partition can be further divided into up to 32 logical drives.

In Storage Foundation for Windows, FastResync is a part of the FlashSnap feature. FR supports resynchronization of mirrors by copying only changes to the temporarily split mirror by using FR logging. This reduces the time it takes to rejoin a split mirror to the mirror set and also reduces the server CPU cycles needed to complete the resynchronization. FastResync can also be used on ordinary mirrored volumes to speed up resynchronization.

An operation in which the failure of one appliance, program, or security gateway causes another to pick up its workload automatically.

Refers to a disk that contains fault tolerant volumes that are created in Windows NT Disk Administrator.

Refers to a RAID volume that was originally created in Windows NT Disk Administrator. These volumes include spanned volumes (volume sets), mirrored volumes (mirror sets), striped volumes (stripe sets), and RAID-5 volumes (stripe sets with parity). The FT refers to fault tolerant, even though some of the volume sets are not fault tolerant. Windows Server 2003 does not support FT volumes.

In Storage Foundation for Windows, when a disk fails, hot relocation automatically moves all subdisks from redundant volumes on the failed disk to hot spare disks, or to free space on other disks if enough space is not available on hot spare disks.

In Storage Foundation for Windows, a hot spot is an area of high I/O activity that may cause bottlenecks in I/O throughput.

A logical drive is a simple volume that resides on an extended partition on a basic disk. Logical drives are limited to the space on the extended partition. They cannot span multiple disks. A logical drive can be formatted and assigned a drive letter.

An extended partition can be subdivided into as many as 32 logical drives. All or part of the free space in an extended partition can be used when creating logical drives.

The number that, when combined with the target ID, uniquely identifies a disk on the port.

In Storage Foundation for Windows, DMP (Dynamic Multipathing) monitors the paths to an array to determine whether they are functioning properly. The monitor interval specifies the time interval for the monitoring of that array.

An advanced file system designed for use specifically within Windows operating systems. It supports file system recovery, extremely large storage media, long file and folder names, and file and folder compression.

Redundant information that is associated with a block of information. 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, the parity information on the good disks can be used to recreate the data on the failed disk.

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 contiguous regions. When a basic disk that contains partitions is upgraded to a dynamic disk, the partitions become simple volumes on the dynamic disk.

In Storage Foundation for Windows, the polling interval is the interval at which volume capacities are checked.

The disk group that contains the computer's boot or system disk. All other dynamic disk groups are called secondary disk groups. If none of the dynamic disk groups on a system contain the boot or system disk, then there is not a primary disk group.

A volume that is created by using unallocated space on a basic disk. Microsoft Windows NT and other operating systems can start from a primary partition. Up to four primary partitions can be created 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. However, the extended partition can be further divided into as many as 32 logical drives.

An advanced file system that is built on the foundation of NTFS. ReFS is supported on Windows Server 2012 and 2012 R2 operating systems only.

Any dynamic disk group that is not primary. A primary disk group is a dynamic disk group that contains the computer's boot or system disk. All other dynamic disk groups are called secondary disk groups.

A simple dynamic volume consists of a single contiguous region (or subdisk) on a single physical disk. Simple dynamic volumes can be extended or mirrored. A simple volume can be extended within the same disk or onto additional disks.

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.

A volume made up of disk space on more than one physical disk. Space can be added to a spanned volume by extending it at any time. Spanned volumes can be created only on dynamic disks. Spanned volumes by themselves are not fault tolerant. However, they can be mirrored to be made fault tolerant.

In Storage Foundation for Windows, the statistics threshold is the minimum amount of I/O per second that a disk or subdisk must have to display an I/O status other than the Low I/O activity status.

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 can be created only on dynamic disks. Striped volumes by themselves are not fault tolerant; however, they can be mirrored to be made fault tolerant. They also can be extended.

Refers to a region of contiguous space on a disk. In Storage Foundation for Windows, subdisks are the basic units in which disk space in a volume is allocated. A disk can be divided into one or more subdisks. Each subdisk represents a specific portion of the volumes on a dynamic disk.

A Storage Foundation for Windows disk may contain multiple subdisks, but subdisks cannot overlap or share the same portions of a disk. Any disk space that is not part of a subdisk is considered to be unallocated space, which can be used to create new volumes.

Subdisks can be moved to improve disk performance.

The partition or volume that has the files needed to load the operating system. It is the same as the active partition or volume. In Windows, the system partition or volume is the one the computer starts from, while the boot volume is the one that has the operating system and support files. The system partition or volume and the boot partition or volume can be the same partition or volume.

The number that, when combined with the LUN, uniquely identifies a disk on the port.

A volume is a logical entity that is made up of a portion or portions of one or more physical disks. A volume can be formatted with a file system and can be accessed by a drive letter or a mount path. Like disks, volumes can be basic or dynamic.

The volume read policy on a dynamic volume allows an administrator to specify either that a particular mirror be used for reads or that all mirrors be read in turn in round-robin fashion for each nonsequential I/O detected.

In Storage Foundation for Windows, the percentage of volume capacity at which a warning message is sent. The default is 80 percent of volume capacity.