Create RAID Virtual Disk (Automatic Physical Disk Select)

Create RAID Virtual Disk (Automatic Physical Disk Select)

This command creates a disk group across the storage array physical disks, and a new virtual disk in the disk group. The storage array RAID controller modules choose the physical disks to be included in the virtual disk.

Important: If you have physical disks with different capacities, you cannot automatically create virtual disks by specifying the driveCount parameter. If you want to create virtual disks with disks of different capacities, see "Create RAID Virtual Disk (Manual Physical Disk Select)".

Syntax

create virtualDisk driveCount=numberOfPhysical Disks raidLevel=(0 | 1 | 3 | 5 | 6) userLabel="virtualDiskName" [driveType=(fibre | SATA | SAS | PATA) capacity=volumeCapacity owner=(a | b) cacheReadPrefetch=(TRUE | FALSE) segmentSize=segmentSizeValue usageHint=(fileSystem | dataBase | multiMedia) enclosureLossProtect=(TRUE | FALSE)]

Parameters

Parameter Description

driveCount
The number of unassigned physical disks that you want to use in the disk group.

raidLevel
The RAID level of the disk group that contains the virtual disk. Valid values are 0, 1, 3, 5, or 6.

userLabel
The name you want to give the new virtual disk. Enclose the new virtual disk name in double quotes (" ").

driveType
Defines the type of physical disk you want to use in the virtual disk. You cannot mix physical disk types. Valid physical disk types are: fibre, SATA, SAS, or PATA.

capacity
The size of the virtual disk you are adding to the storage array. Size is defined in units of bytes, KB, MB, or GB.

owner
The RAID controller module that owns the virtual disk. Valid RAID controller module identifiers are a or b where a is the RAID controller module in slot A and b is the RAID controller module in slot B. If you do not specify an owner, the RAID controller module firmware determines the owner.

cacheReadPrefetch
This parameter turns on or turns off cache read prefetch. To turn off cache read prefetch, set this parameter to FALSE. To turn on cache read prefetch, set this parameter to TRUE.

segmentSize
The amount of data (in kilobytes) the RAID controller module writes on a single physical disk in a virtual disk before writing data on the next physical disk. Valid values are 8, 16, 32, 64, 128, 256, or 512.

usageHint
This parameter sets both the cacheReadPrefetch and segmentSize parameters to default values. The default values are based on the typical I/O usage pattern of the application using the virtual disk. Valid values are fileSystem, dataBase, or multiMedia.

enclosureLossProtect
Specifies that enclosure loss protection will be enforced when creating the disk group. To enforce enclosure loss protection, set this parameter to TRUE. The default setting is FALSE.

Notes

The driveCount parameter enables you to choose the number of physical disks you want to use in the disk group. You do not have to specify the physical disks by enclosure ID and slot ID. The RAID controller modules choose the specific physical disks to use for the disk group.

The owner parameter defines which RAID controller module owns the virtual disk.

If you do not specify a capacity, all physical disk capacity available in the disk group is used. If you do not specify capacity units, bytes are used as the default.

The size of a segment determines how many data blocks the RAID controller module writes on a single physical disk in a virtual disk before writing data on the next physical disk. Each data block stores 512 bytes of data. A data block is the smallest unit of storage. The size of a segment determines how many blocks it contains. For example, an 8 KB segment holds 16 data blocks; a 64 KB segment holds 128 data blocks. When you enter a value for the segment size, the value is checked against the supported values provided by the RAID controller module at run time. If the value you enter is not valid, the RAID controller module returns a list of valid values. For optimal performance in a multi-user database or file system storage environment, set your segment size to minimize the number of physical disks needed to satisfy a data transfer request. Using a single physical disk for a single request leaves other physical disks available to simultaneously service other requests. If the virtual disk is in a single-user large data transfer environment (such as multi-media) performance is maximized when a single data transfer request is serviced with a single data stripe. (A data stripe is the segment size multiplied by the number of physical disks in the disk group that are used for data transfer.) In this case, multiple disks are used for the same request, but each disk is only accessed once.

If you set the cache block size to 16, then you cannot create a virtual disk with a segment size of 8.

Cache read prefetch enables the RAID controller module to copy additional data blocks into cache while the RAID controller module reads and copies data blocks requested by the host from disk into cache. This action increases the chance that a future request for data can be fulfilled from cache. Cache read prefetch is important for multimedia applications that use sequential data transfers. The number of additional data blocks that the RAID controller module reads into cache is determined by the storage array configuration settings that you use. Valid values for the cacheReadPrefetch parameter are TRUE or FALSE.

You do not have to enter a value for the cacheReadPrefetch parameter or the segmentSize parameter. If you do not enter a value, the firmware uses the usageHint parameter with the fileSystem argument as the default value. If you choose to enter a value for the cacheReadPrefetch parameter or a value for the segmentSize parameter, you cannot use the usageHint parameter.

For enclosure loss protection to work, each physical disk in a disk group must be on separate enclosure. If you set enclosureLossProtect to true and have selected more than one physical disk from any one enclosure, the storage array will return an error. If you set enclosureLossProtect to false, the storage array will perform operations, but the disk group you create may not have enclosure loss protection.

Enclosure loss protection is not valid when creating virtual disks on existing disk groups.

Minimum Firmware Level

5.20
7.10 adds RAID 6 and SAS

Parameter	Description
`driveCount`	The number of unassigned physical disks that you want to use in the disk group.
`raidLevel`	The RAID level of the disk group that contains the virtual disk. Valid values are 0, 1, 3, 5, or 6.
`userLabel`	The name you want to give the new virtual disk. Enclose the new virtual disk name in double quotes (" ").
`driveType`	Defines the type of physical disk you want to use in the virtual disk. You cannot mix physical disk types. Valid physical disk types are: fibre, SATA, SAS, or PATA.
`capacity`	The size of the virtual disk you are adding to the storage array. Size is defined in units of bytes, KB, MB, or GB.
`owner`	The RAID controller module that owns the virtual disk. Valid RAID controller module identifiers are a or b where a is the RAID controller module in slot A and b is the RAID controller module in slot B. If you do not specify an owner, the RAID controller module firmware determines the owner.
`cacheReadPrefetch`	This parameter turns on or turns off cache read prefetch. To turn off cache read prefetch, set this parameter to FALSE. To turn on cache read prefetch, set this parameter to TRUE.
`segmentSize`	The amount of data (in kilobytes) the RAID controller module writes on a single physical disk in a virtual disk before writing data on the next physical disk. Valid values are 8, 16, 32, 64, 128, 256, or 512.
`usageHint`	This parameter sets both the cacheReadPrefetch and segmentSize parameters to default values. The default values are based on the typical I/O usage pattern of the application using the virtual disk. Valid values are fileSystem, dataBase, or multiMedia.
`enclosureLossProtect`	Specifies that enclosure loss protection will be enforced when creating the disk group. To enforce enclosure loss protection, set this parameter to TRUE. The default setting is FALSE.