Show Storage Subsystem Auto Configure

This command shows the default auto-configuration that the storage subsystem creates if you run the autoConfigure storageSubsystem command. If you want to determine whether the storage subsystem can support specific properties, enter the parameter for the properties when you run this command. You do not need to enter any parameters for this command to return configuration information.

Syntax

show storageSubsystem autoConfiguration  
[driveType=(fibre | SATA | SAS | PATA)  
raidLevel=(0 | 1 | 3 | 5 | 6) 
arrayWidth=numberOfDrives 
arrayCount=numberOfArrays 
logicalDrivesPerGroupCount=numberOfLogicalDrivesPerGroup 
hotSpareCount=numberOfHotspares  
segmentSize=segmentSizeValue  
cacheReadPrefetch=(TRUE | FALSE)]

Parameters

Parameter Description
driveType The type of disk drives that you want to use for the storage subsystem. Valid disk drive types are fibre, SATA, SAS, or PATA. The driveType parameter is not required if only one type of disk drive is in the storage subsystem.
raidLevel The RAID level of the array that contains the disk drives in the storage subsystem. Valid RAID levels are 0, 1, 3, 5, or 6.
arrayWidth The number of disk drives in an array in the storage subsystem, which depends on the capacity of the disk drives. Use integer values.
arrayCount The number of arrays in the storage subsystem. Use integer values.
logicalDrivesPerGroupCount The number of equal-capacity logical drives per array. Use integer values.
hotSpareCount The number of hot spares that you want in the storage subsystem. Use integer values.
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.
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.

Notes

If you do not specify any properties, this command returns the RAID Level 5 candidates for each disk drive type. If RAID Level 5 candidates are not available, this command returns candidates for RAID Level 6, RAID Level 3, RAID Level 1, or RAID Level 0. When you specify auto configuration properties, the controllers validate that the firmware can support the properties.

Disk Drives

An array is a set of disk drives that are logically grouped together by the controllers in the storage subsystem. The number of disk drives in an array is a limitation of the controller firmware. You should adhere to the 30-disk drive limit and to the 2-TB size maximum for the array, which some operating systems require. The table relates disk drive capacity to the number of disk drives in an array.

Disk Drive Size Maximum Number of Disk Drives in the Array
18 GB 30 disk drives
36 GB 30 disk drives
73 GB 28 disk drives
180 GB 11 disk drives

A 73-GB disk drive or a 180-GB disk drive does not report exactly 73 GB or 180 GB as its capacity.

Hot Spares

Hot spare disk drives can replace any failed disk drive in the storage subsystem. A hot spare disk drive must have capacity greater than or equal to any disk drive that can fail. If a hot spare disk drive is smaller than a failed disk drive, you cannot use the hot spare disk drive to rebuild the data from the failed disk drive. Hot spare disk drives are available only for RAID Level 1, RAID Level 3, RAID Level 5, or RAID Level 6.

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.

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 drive 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.

Minimum Firmware Level

6.10

7.10 adds RAID Level 6 capability and removes hot spare limits.