Dell PowerVault MD3260i - Manual (Page 43)

• Size of each segment on the physical disks
After defining these parameters, the MD Storage Manager automatically creates the disk groups, virtual disks, and hot
spares. The RAID controller modules assign disk group and virtual disk numbers as they are created. After MD Storage
Manager creates the initial configuration, you can use the set virtualDisk command to define virtual disk labels.
Before running the autoConfigure storageArray command, run the show storageArray
autoConfigure command. The show storageArray autoConfigure command returns a list of parameter
values that MD Storage Manager uses to create a storage array. Change any of the parameter values by entering new
values for the parameters when you run the autoConfigure storageArray command. If you are satisfied with
the parameter values that the show storageArray autoConfiguration command returns, run the
autoConfigure storageArray command without new parameter values.
The following syntax is the general form of autoConfigure storageArray command:
autoConfigure storageArray [physicalDiskType=
(SAS) raidLevel=(0 | 1 | 5 | 6) | diskGroupWidth=
numberOfPhysicalDisks | diskGroupCount=
numberOfDiskGroups | virtualDisksPerGroupCount=
numberOfVirtualDisksPerGroup | hotSpareCount=
numberOfHotspares | segmentSize=segmentSizeValue]
NOTE: All parameters are optional. You can use one or all of the parameters as needed to define your
configuration.
When you use the autoConfigure storageArray command without specifying the number of disk groups, the
firmware determines how many virtual disks and disk groups to create. The firmware creates one disk group and one
virtual disk up to the maximum number that the storage array can support. When you specify the number of disk groups,
the firmware creates only that number of disk groups. When you create more than one disk group, all of the disk groups
have the same number of physical disks and the same number of virtual disks.
• The diskGroupWidth parameter defines the number of unassigned physical disks wanted for each new disk
group.
• The diskGroupCount parameter defines the number of new disk groups wanted in the storage array.
• The virtualDisksPerGroupCount parameter defines the number of virtual disks wanted in each disk
group.
• The hotSpareCount parameter defines the number of hot spares wanted in each disk group.
• The segmentSize parameter defines the amount of data in kilobytes that the RAID controller module writes
on a single physical disk in a virtual disk before writing data on the next physical disk. The smallest units of
storage are data blocks. Each data block stores 512 bytes of data. The size of a segment determines how many
data blocks that it contains. An 8-KB segment holds 16 data blocks. A 64-KB segment holds 128 data blocks.
Valid values for the segment size are 8, 16, 32, 64, 128, 256, and 512.
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.
If the virtual disk is for a single user with large I/O requests (such as multimedia), performance is maximized when a
single I/O request can be 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 storage. In this environment, multiple physical disks are used for
the same request, but each physical disk is accessed only once.
For optimal performance in a multi-user database or file system storage environment, set the segment size to minimize
the number of physical disks needed to satisfy an I/O request. Using a single physical disk for a single request leaves
other physical disks available to simultaneously service other requests.
After you have finished creating the disk groups and virtual disks by using the autoConfigure storageArray
command, you can further define the properties of the virtual disks in a configuration using the set virtualDisk
command. (See Modifying Your Configuration.)
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