mkmdiskgrp

The mkmdiskgrp command creates a new managed disk group.

Syntax


>>- svctask -- -- mkmdiskgrp -- --+-------------------------+--->
                                  '- -name -- new_name_arg -'   

>-- --+---------------------------------+-- -------------------->
      '- -mdisk --+- mdisk_id_list ---+-'      
                  '- mdisk_name_list -'        

>-- -ext -- extent_size ---------------------------------------->

>--+--------------------------------------------------+--------->
   '- -warning --disk_size |--disk_size_percentage--%-'   

>--+-------------------+---------------------------------------><
   '- -unit --+- b --+-'   
              +- kb -+     
              +- mb -+     
              +- gb -+     
              +- tb -+     
              '- pb -'

Parameters

-name new_name_arg: (Optional) Specifies a name to assign to the new group.
-mdisk mdisk_id_list | mdisk_name_list: (Optional) Specifies a colon-separated list of managed disk IDs or names to add to the group. You can create an empty MDisk group by not specifying the -mdisk parameter.
-ext extent_size: (Required) Specifies the size of the extents for this group in MB. The extent_size parameter must be one of the following values: 16, 32, 64, 128, 256, 512, 1024, or 2048 (MB).
-warning disk_size | disk_size_percentage%: (Optional) Generates a warning when the used disk capacity in the MDisk group first exceeds the specified threshold. You can specify a disk_size integer, which defaults to megabytes (MB) unless the -unit parameter is specified; or you can specify a disk_size%, which is a percentage of the MDisk group size. To disable warnings, specify 0 or 0%. The default value is 0.
-unit b | kb | mb | gb | tb | pb: (Optional) Specifies the data units for the -warning parameter.

Description

The mkmdiskgrp command creates a new managed disk group and assigns the group name if specified. The ID of the new group is returned if the command is successful. Managed disk groups are collections of managed disks. Each group is divided into chunks, called extents, which are used to create virtual disks.

Optionally, you can specify a list of managed disks that will be added to this group. These managed disks cannot belong to another group, and they must have a mode of unmanaged. Use the svcinfo lsmdiskcandidate command to get a list of suitable candidates.

Each managed disk that is a member of this group is split into extents. The storage that is available on these disks is added to a pool of extents that is available in this group. When a virtual disk is created from this group, free extents from the pool are used, in accordance with the policy used when the virtual disk was first created.

All managed disks subsequently added to this group are split into extents of the same size as the size that is assigned to the group.

When choosing an extent size, take into account the amount of storage you want to virtualize in this group. The system maintains a mapping of extents between virtual disks and managed disks. The cluster can only manage a finite number of extents (4 194 304). One cluster can virtualize the following number of extents:

64 TB – if all managed disk groups have extent sizes of 16 MB.
2 PB – if all managed disk groups have extent sizes of 512 MB.

Important: The extent size for the MDisk group can also limit VDisk size. Consider the maximum VDisk size you want to use when creating MDisk groups. SAN Volume Controller MDisk groups information provides the maximum VDisk capacity for each extent size.

Note: When an image mode VDisk is created, the MDisk group increases in capacity by the size of the image mode VDisk (not the MDisk capacity), because the image mode VDisk might be smaller than the MDisk itself. If an extent is migrated from the image mode VDisk or MDisk to elsewhere in the group, the VDisk becomes a striped VDisk (no longer image mode). At this point the available capacity might increase, because the extra capacity available on the MDisk (for example, the capacity that was not part of the image mode VDisk) becomes available.

Note: When you create an MDisk group with a new solid-state drive (SSD), the new SSD is automatically formatted and set to a block size of 512 bytes.

An invocation example

svctask mkmdiskgrp -mdisk mdisk13 -ext 512

The resulting output

MDisk Group, id [1], successfully created

An invocation example

svctask mkmdiskgrp -mdisk mdisk0:mdisk1:mdisk2:mdisk3 -ext 32

The resulting output

MDisk Group, id [0], successfully created