Dell PowerVault MD3420 - Manual (Page 48)

• 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.)
Example Of The Auto Configuration Command
client>smcli 123.45.67.89 -c "autoConfigure
storageArray physicalDiskType=SAS raidLevel=5
diskGroupWidth=8 diskGroupCount=3
virtualDisksPerGroupCount=4 hotSpareCount=2
segmentSize=8;"
The command in this example creates a storage array configuration that uses SAS physical disks set to
RAID level 5. Three disk groups are created. Each disk group consists of eight physical disks configured
into four virtual disks. The storage array has two hot spares, and segment size for each virtual disk is 8 KB.
Modifying Your Configuration
After creating your initial configuration, modify the properties of the configuration to ensure that it meets
your requirements for data storage. Use the following commands to modify the properties of your
configuration:
• autoConfigure storageArray
• create virtualDisk
Use the set commands to modify a storage array configuration. This section explains how to modify the
following properties:
• Storage array password
• Simple Mail Transport Protocol (SMTP) and Simple Network Management Protocol (SNMP) alerts
• RAID controller module clocks
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