This command creates a array across the disk drives in the storage subsystem, and a new logical drive in the array. The storage subsystem controllers choose the disk drives to be included in the logical drive.
Syntax
Important: If you have disk drives with different capacities, you cannot
automatically create logical drives by specifying the driveCount parameter. If you want to create logical drives with disk drives of different capacities, see “Create RAID Logical Drive (Manual Drive Select)” on page 66.
create logicalDrive driveCount=numberOfDrives arrayUserLabel=arrayName
raidLevel=(0 | 1 | 3 | 5 | 6) userLabel=logicalDriveName DriveType=(fibre | SATA | SAS)
DriveMediaType=(HDD | SSD | unknown | allMedia) capacity=logicalDriveCapacity
owner=(a | b)
cacheReadPrefetch=(TRUE | FALSE) segmentSize=segmentSizeValue
usageHint=(fileSystem | dataBase | multiMedia) enclosureLossProtect=(TRUE | FALSE)
enclosureLossProtect=(TRUE | FALSE) drawerLossProtect=(TRUE | FALSE) dssPreAllocate=(TRUE | FALSE)]
securityType=(none | capable | enabled)]
Parameters
Parameter Description
driveCount The number of unassigned disk drives that you want to use in the array.
raidLevel The RAID level of the array that contains the logical drive. Valid values are 0, 1, 3, 5, or 6.
userLabel The name that you want to give to the new logical drivev . Enclose the new logical drive name in double quotation marks (“ ”).
driveType The type of disk drive that you want to use in the logical drive.
You cannot mix disk drive types. Valid disk drive types are fibre, SATA, or SAS.
DriveMediaType The type of disk drive medium that you want to use for the create RAID logical drive. Values are
v HDD – Use this option when you have hard disk drives in the expansion drawer.
v SSD – Use this option when you have solid state disk drives in the expansion drawer.
v unknown – Use if you are not sure what types of disk drive media are in the expansion drawer.
v allMedia – Use this option when you want to use all types of disk drive media that are in the expansion drawer.
Use this parameter only when you use the DriveCount parameter.
If you have only one type of disk drive media, you do not need to use this parameter. You must use this parameter when you have more than one type of disk drive media in your storage subsystem.
capacity The size of the logical drive that you are adding to the storage subsystem. Size is defined in units of bytes, KB, MB, GB, or TB.
owner The controller that owns the logical drive. Valid controller identifiers are a or b, where a is the controller in slot A, and b is the controller in slot B. If you do not specify an owner, the controller firmware determines the owner.
cacheReadPrefetch The setting to turn on or turn 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 KB) that the controller writes on a single disk drive in a logical drive before writing data on the next disk drive. Valid values are 8, 16, 32, 64, 128, 256, or 512.
Parameter Description
usageHint The setting for both cacheReadPrefetch parameter and the
segmentSizeparameter to be default values. The default values are based on the typical I/O usage pattern of the application that is using the logical drive. Valid values are fileSystem, dataBase, or multiMedia.
enclosureLossProtect The setting to enforce enclosure loss protection when you create the array. To enforce enclosure loss protection, set this parameter to TRUE. The default setting is FALSE.
dssPreAllocate The setting to make sure that reserve capacity is allocated for future segment size increases. The default value is TRUE.
securityType The setting to specify the security level when creating the arrays and all associated logical drives. These settings are valid:
v none—The array and logical drives are not secure.
v capable—The arrays and logical drives are capable of having security set, but security has not been enabled.
v enabled—The array and logical drives have security enabled.
Notes
The driveCount parameter lets you choose the number of disk drives that you want to use in the array. You do not need to specify the disk drives by enclosure ID and slot ID. The controllers choose the specific disk drives to use for the array.
The owner parameter defines which controller owns the logical drive.
If you do not specify a capacity using the capacity parameter, all of the disk drive capacity that is available in the array is used. If you do not specify capacity units, bytes is used as the default value.
Cache Read Prefetch
Cache read prefetch lets the controller copy additional data blocks into cache while the controller reads and copies data blocks that are requested by the host from the disk drives 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 configuration settings for the storage subsystem that you use determine the number of additional data blocks that the controller reads into cache. Valid values for the cacheReadPrefetch parameter are TRUE or FALSE.
Segment Size
The size of a segment determines how many data blocks that the controller writes on a single disk drive in a logical drive before writing data on the next disk drive.
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 data blocks that 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 that are provided by the controller at run time. If the value that
you entered is not valid, the controller returns a list of valid values. Using a single disk drive for a single request leaves other disk drives available to simultaneously service other requests.
If the logical drive is in an environment where a single user is transferring large units of data (such as multimedia), performance is maximized when a single data transfer request is serviced with a single data stripe. (A data stripe is the segment size that is multiplied by the number of disk drives in the array that are used for data transfers.) In this case, multiple disk drives are used for the same request, but each disk drive is accessed only once.
For optimal performance in a multiuser database or file system storage
environment, set your segment size to minimize the number of disk drives that are required to satisfy a data transfer request.
You do not need to enter a value for the cacheReadPrefetch parameter or the segmentSize parameter. If you do not enter a value, the controller firmware uses the usageHint parameter with fileSystem as the default value. Entering a value for the usageHint parameter and a value for the cacheReadPrefetch parameter or a value for the segmentSize parameter does not cause an error. The value that you enter for the cacheReadPrefetch parameter or the segmentSize parameter takes priority over the value for the usageHint parameter.