Description
This command creates either a free-capacity disk group
or a disk group with one virtual disk when you enter a set of assigned
physical disks.
Syntax
create diskGroup
physicalDisks=(
enclosureID1,drawerID1,slotID1
enclosureID2,slotID2... enclosureIDn,drawerIDn,slotIDn
)
raidLevel=(0 | 1 | 5 | 6)
userLabel=”
diskGroupName”
[driveMediaType=(HDD | SSD | unknown | allMedia)
capacity=
virtualDiskCapacity
owner=(0 | 1)
cacheReadPrefetch=(TRUE | FALSE)
segmentSize=
segmentSizeValue
usageHint=(fileSystem | dataBase | multiMedia)
enclosureLossProtect=(TRUE | FALSE)
drawerLossProtect=(TRUE | FALSE)
securityType=(none | capable | enabled)]
[dataAssurance=(none | enabled)]
Parameters
Parameter |
Description |
physicalDisks
|
The physical disks that you want to assign to
the disk group that you want to create. Specify the enclosure ID value
and the slot ID value for each physical disk that you assign to the
disk group. Enclosure ID values are
0 to
99. Drawer ID values are
0 to
4. Slot
ID values are
0 to
31. Enclose the enclosure
ID values and the slot ID values in parentheses.
|
raidLevel
|
The RAID level of the disk group that contains
the virtual disk. Valid values are
0,
1,
5, or
6.
|
userLabel
|
The alphanumeric identifier (including - and _)
that you want to give the new disk group. Enclose the disk group identifier
in double quotation marks (“ ”).
|
driveMediaType
|
The type of physical disk media that you want
to use for the disk group. Valid physical disk media consists of:
- HDD — Use this option when you have hard disk drives
in the expansion enclosure.
- SSD — Use this option when you have solid state physical
disks in the expansion enclosure.
- unknown —Use if you are not sure what types of physical
disk media are in the expansion enclosure.
- allMedia — Use this option when you want to use all
types of physical disk media that are in the expansion enclosure.
|
physicalDiskType
|
The type of physical disk that you want to use
in the virtual disk. You cannot mix physical disk types. The valid
physical disk type is
SAS. You must specify
a physical disk type.
|
capacity
|
The size of the virtual disk that you are adding
to the storage array. Size is defined in units of bytes,
KB,
MB,
GB, or
TB. The
following examples show the syntax:
capacity=500 bytes
capacity=2 GB
-
NOTE: A space must be added
between the last digit and the size (bytes, KB, MB, or GB) for values
greater than 9. If you do not specify a capacity, all the available
physical disk capacity in the disk group is used. If you do not specify
the capacity unit, bytes is used as the default unit.
|
owner
|
The setting for which RAID controller module owns
the disk group. Valid RAID controller module identifier values are
0 and
1. The identifier value is
0 for the RAID controller module on the top and
1 for
the RAID controller module on the bottom when viewed from the rear
of the enclosure. If you do not specify an owner, the RAID controller
module 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 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
|
The setting for both the
cacheReadPrefetch parameter and the
segmentSize parameter to be default
values. The default values are based on the typical I/O usage pattern
of the application that is using the virtual disk. Valid values are
fileSystem,
dataBase, or
multiMedia.
|
enclosureLossProtect
|
The setting to enforce enclosure loss protection
when you create the disk group. To enforce enclosure loss protection,
set this parameter to
TRUE. The default value is
FALSE.
|
drawerLossProtect
|
The setting to enforce drawer loss protection
when you create the disk group. To enforce drawer loss protection,
set this parameter to
TRUE. The default value is
FALSE.
|
securityType
|
The setting to specify the security level when
creating the disk groups and all associated virtual disks.
-
none—The disk group and virtual disks
are not secure.
-
capable—The disk group and virtual
disks are capable of having security set, but security has not been
enabled.
-
enabled—The disk group and virtual
disks have security enabled.
|
dataAssurance
|
The setting to specify that a disk
group, and the virtual disks within the disk group, has data assurance
protection to make sure that the data maintains its integrity. When
you use this parameter, only protected physical disks can be used
for the disk group. These settings are valid:
-
none - The disk group does not have data assurance
protection.
-
enabled - The disk group has data assurance
protection. The disk group supports protected information and is formatted
with protection information enabled.
-
NOTE: This option is only valid
for enablement, if the drives support DA.
|
Additional
Information
Cache Read Prefetch
The
cacheReadPrefetch command
lets the RAID controller module copy additional data blocks into cache
while the RAID controller module reads and copies data blocks that
are requested by the host from the physical disks into cache. This
action increases the chance that a future request for data can be
fulfilled from cache.
CacheReadPrefetch is important
for multimedia applications that use sequential data transfers. The
configuration settings for the storage array that you use determine
the number of additional data blocks that the RAID controller module
reads into cache. Valid values for the
cacheReadPrefetch parameter are
TRUE or
FALSE.
You do not need to enter a value for the
cacheReadPrefetch parameter or the
segmentSize parameter. If you do
not enter a value, the RAID controller module 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.
Segment Size
The size
of a segment determines how many data blocks that 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 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 RAID controller module at run time. If the value that you entered
is not valid, the RAID controller module returns a list of valid values.
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 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 physical disks in the disk group that are used for
data transfers. In this case, multiple physical disks are used for
the same request, but each physical disk 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 physical disks that are required to satisfy a data transfer
request.
Security Type
The
securityType parameter is valid for
physical disks that are capable of self-encrypting disk (SED). With
SED, the RAID controller module firmware can create a key and activate
the physical disk security feature. The physical disk security feature
encrypts data as the data is written to the physical disk and decrypts
the data as the data is read from the physical disk. Without the key
created by the RAID controller module, the data written to the physical
disk is inaccessible.
Before you can set the
securityType parameter to capable or enabled, you must create
a storage array security key. Use the
create storageArray securityKey command to create a storage array security key. The following commands
are related to the security key:
-
create storageArray securityKey
-
set storageArray securityKey
-
start secureErase (physicalDisk | physicalDisks)
-
enable diskGroup [diskGroupName] security
Secure-capable drives can be either SED drives or Federal Information
Processing Standard (FIPS) drives. Use the
securePhysicalDisks parameter to specify the type of secure physical disks to use. The
values you can use are fips and sed.
Enclosure
Loss Protection and Drawer Loss Protection
For enclosure loss protection to work, each physical disk in a disk
group must be in a separate enclosure. If you set the
enclosureLossProtect parameter to
TRUE and have selected more than one
physical disk from any one enclosure, the storage array returns an
error. If you set the
enclosureLossProtect parameter
to
FALSE, the storage array performs operations, but
the disk group that you create might not have enclosure loss protection.
Enclosure loss protection is not valid when you create virtual disks
on existing disk groups.
The
drawerLossProtect parameter defines if data on a virtual disk is accessible if a drawer
fails. When you assign the physical disks, if you set the
drawerLossProtect parameter to
TRUE and select more than one physical
disk from any one drawer, the storage array returns an error. If you
set the
drawerLossProtect parameter to
FALSE, the storage array performs operations, but the disk group that
you create might not have drawer loss protection. You must set the
enclosureLossProtect parameter and the
drawerLossProtect parameter to the same value. Either both the parameters must be
TRUE or both must be
FALSE. If the
enclosureLossProtect parameter and the
drawerLossProtect parameter are set to different values, the storage array returns
an error.