mkvdisk

Use the mkvdisk command to create sequential, striped, or image mode volume objects. When they are mapped to a host object, these objects are seen as disk drives with which the host can run I/O operations. The first syntax diagram is for striped or sequential volumes and the second syntax diagram for image mode volumes. Use the mkvolume command for a simplified way of creating high availability volumes. Use the mkimagevolume command for a simplified way of creating an image mode volume, importing existing data from a managed disk.

Syntax

Note: The first syntax diagram depicts the creation of a sequential or striped mode volume. The second syntax diagram depicts the creation of an image mode volume.

Create a sequential or striped mode volume.

Create an image mode volume.

Parameters

-mdiskgrp mdisk_group_id_list | mdisk_group_name_list

(Required) Specifies one or more storage pools to use when you are creating this volume. If you are creating multiple copies, you must specify one storage pool per copy. The primary copy is allocated from the first storage pool in the list.

Note: If you are creating volumes in a pool that is used as a Safeguarded backup location, only one pool can be specified. Mirrored volumes are not supported.

-udid vdisk_udid

(Optional) Specifies the unit number udid for the disk. The udid is an identifier that is required to support OpenVMS hosts; no other systems use this parameter. Valid options are a decimal number 0 - 32 767, or a hexadecimal number 0 - 0x7FFF. A hexadecimal number must be preceded by 0x (for example, 0x1234).

-vtype seq | striped | image

(Optional) Specifies the virtualization type. When you create sequential or image mode volumes, you must also specify the -mdisk parameter. You cannot use -vtype seq or

-vtype
image

in a data reduction pool. The default virtualization type is striped.

-iogrp io_group_id | io_group_name (Deprecated)

-accessiogrp iogroup_id_list | iogroup_name_list (Deprecated)

-size disk_size

(Required for sequential or striped volume creation) (Optional for image volume creation) Specifies the capacity of the volume, which is used with the value of the unit. All capacities, including changes, must be in multiples of 512 bytes. An error occurs if you specify a capacity that is not a multiple of 512. It can happen only when byte units (-b) are used. However, an entire extent is reserved even if it is only partially used. The default capacity is in MB. You can specify a capacity of 0. Specify the size in bytes in multiples of logical block address (LBA) sizes.

Note: If you do not specify the -size parameter when you create an image mode disk, the entire MDisk capacity is used.

-fmtdisk

(Optional) Specifies that the volume is formatted. This parameter is no longer required for any volumes.

This parameter is not required when you create standard-provisioned volumes. The format operation is automatically applied to standard-provisioned volumes unless you specify -nofmtdisk parameter. The format operation sets the extents that make up this volume to all zeros after it is created. This process takes place in the background concurrently with host I/O operations on the new volume.

Remember: Formatting is on by default for single copy, standard-provisioned, and non-image mode volumes. You cannot format an image mode volume.

The format operation completes asynchronously. You can query the status by using the lsvdiskprogress comm. You cannot specify this parameter with the -vtype image parameter.

This parameter is not required when you create thin-provisioned volumes. Thin-provisioned volumes return zeros for extents that are not written to. No format operation is required. This parameter also synchronizes mirrored copies by default.

-nofmtdisk

(Optional) Specifies that formatting be turned off for the new volume.

Remember: Formatting is on by default for single copy, standard-provisioned, and non-image mode volumes, and you can specify this parameter to turn it off.

-rsize disk_size | disk_size_percentage% | auto

(Optional) Defines how much physical space is initially allocated to the thin-provisioned or compressed volume. This parameter makes the volume thin-provisioned; otherwise, the volume is standard-provisioned. Specify the disk_size | disk_size_percentage value by using an integer, or an integer immediately followed by the percent character (%). Specify the units for a disk_size integer by using the -unit parameter; the default is MB. The -rsize value can be greater than, equal to, or less than the size of the volume. The auto option creates a volume copy that uses the entire size of the MDisk.

If you specify the -rsize auto option, you must also specify the -vtype image option. If you specify , -import you must specify -rsize.

If the volume is in a data reduction storage pool, the value of the -rsize parameter will be ignored in mkvdisk. Only its presence or absence is used to determine whether the disk is a data reduction volume copy or a thick volume copy.

-warning disk_size | disk_size_percentage%

(Optional) Requires that the -rsize parameter also be specified. Specifies a threshold at which a warning error log is generated for volume copies. A warning is generated when the used disk capacity on the thin-provisioned copy first exceeds the specified threshold.

Note: You cannot specify this parameter for thin-provisioned or compressed volumes that are in data reduction pools.

You can specify a disk_size integer, which defaults to MBs unless the -unit parameter is specified. Or you can specify a disk_size%, which is a percentage of the volume size.

Important: If -autoexpand is:

Enabled, the default value for -warning is 80% of the volume capacity.
Not enabled, the default value for -warning is 80% of the real capacity.

To disable warnings, specify 0.

-autoexpand

(Optional) Specifies that thin-provisioned copies automatically expand their real capacities by allocating new extents from their storage pool. Requires that the -rsize parameter also be specified. If the -autoexpand parameter is specified, the -rsize parameter specifies a capacity that is reserved by the copy. It protects the copy from going offline when its storage pool runs out of space by having the storage pool to use this reserved space first.

The parameter has no immediate effect on image mode copies. However, if the image mode copy is later migrated to managed mode, the copy is then automatically expanded.

-grainsize 32 | 64 | 128 | 256

(Optional) Sets the grain size (KB) for a thin-provisioned volume. This parameter also requires that the -rsize parameter be specified. If you are using the thin-provisioned volume in a FlashCopy® map, use the same grain size as the map grain size for best performance. If you are using the thin-provisioned volume directly with a host system, use a small grain size. The grain size value must be 32, 64, 128, or 256 KB. The default is 256 KB.

If the volume to be created is a thin-provisioned and compressed volume in a data reduction storage pool, the -grainsize parameter cannot be used. This type of volume will be created with a grain size of 8 KB.

-compressed

(Optional) Enables compression for the volume. This parameter must be specified with -rsize and cannot be specified with -grainsize.

-import

(Optional) Imports a thin-provisioned volume from the MDisk. If you specify, -import you must also specify -rsize.

-copies num_copies

(Optional) Specifies the number of copies to create. The num_copies value can be 1 or 2. Setting the value to 2 creates a mirrored volume. The default value is 1.

-createsync

(Optional) Creates copies in sync. Use this parameter if you already formatted the MDisks, or when read stability to unwritten areas of the volume is not required.

-syncrate syncrate

(Optional) Specifies the copy synchronization rate. A value of (0) prevents synchronization. The default value is 50. See Table 1 for the supported -syncrate values and their corresponding rates. Use this parameter to alter the rate at which the standard-provisioned volume or mirrored volume format before synchronization.

-mirrorwritepriority latency | redundancy

(Optional) Specifies how to configure the mirror write algorithm priority. If not specified, the default value is latency.

Choosing latency means a copy that is slow to respond to a write input/output (I/O) becomes unsynchronized, and the write I/O completes if the other copy successfully writes the data.
Choosing redundancy means a copy that is slow to respond to a write I/O synchronizes completion of the write I/O with the completion of the slower I/O to maintain synchronization.

-mdisk mdisk_id_list | mdisk_name_list

(Optional) Specifies one or more managed disks. For sequential and image mode volumes, the number of MDisks must match the number of copies. For sequential mode volumes, each MDisk must belong to the specified storage pool. For striped volumes, you cannot specify the -mdisk parameter if the -copies value is greater than 1.

When you create a single copy striped volume, you can specify a list of MDisks to stripe across.

You must use this parameter to specify an MDisk that has a mode of unmanaged.

-node node_id | node_name

(Optional) Specifies the preferred node ID or the name for I/O operations to this volume. You can use the -node parameter to specify the preferred access node.

Note: This parameter is evaluated by multipath device drivers. The system chooses a default if you do not supply this parameter.

-unit b | kb | mb | gb | tb | pb

(Optional) Specifies the data units to use along with the capacity that is specified by the -size and -rsize parameters. The default unit type is MB.

-name new_name_arg

(Optional) Specifies a name to assign to the new volume.

-cache readwrite | readonly | none

(Optional) Specifies the caching options for the volume. Valid entries are:

readwrite enables the cache for the volume.
readonly disables write caching while allowing read caching for a volume.
none disables the cache mode for the volume.

The default is readwrite.

-tier tier0_flash | tier1_flash | tier_enterprise | tier_nearline | tier_scm

(Optional) Specifies the MDisk tier when an image mode copy is added. This parameter is valid only when -vtype is image.

tier0_flash: Specifies a tier0_flash hard disk drive or an external MDisk for the newly discovered or external volume.
tier1_flash: Specifies an tier1_flash (or flash drive) hard disk drive or an external MDisk for the newly discovered or external volume.
tier_enterprise: Specifies a tier_enterprise hard disk drive or an external MDisk for the newly discovered or external volume.
tier_nearline: Specifies a tier_nearline hard disk drive or an external MDisk for the newly discovered or external volume.
tier_scm: Specifies a tier_scm hard disk drive or an external MDisk for the newly discovered or external volume.

ssd: Specifies an SSD (or flash drive) hard disk drive or an external MDisk for the newly discovered or external volume.
nearline: Specifies a nearline hard disk drive or an external MDisk for the newly discovered or external volume.
enterprise: Specifies an enterprise hard disk drive or an external MDisk for the newly discovered or external volume.

Note: This action applies to both copies if you are creating a mirrored volume with two image mode copies by using this command.

-easytier on | off

Determines whether the IBM® Easy Tier® function is allowed to move extents for this volume.

Note: The -easytier parameter must be followed by either on or off:

If set to on, then Easy Tier functions are active.
If set to off, then Easy Tier functions are inactive.

-udid vdisk_udid

-size disk_size

(Required for sequential or striped volume creation) (Optional for image volume creation) Specifies the capacity of the volume, which is used with the value of the unit. All capacities, including changes, must be in multiples of 512 bytes. An error occurs if you specify a capacity that is not a multiple of 512. It happens when byte units (-b) are used. However, an entire extent is reserved even if it is only partially used. The default capacity is in MB. You can specify a capacity of 0. Specify the size in bytes in multiples of logical block address (LBA) sizes.

Note: If you do not specify the -size parameter when you create an image mode disk, the entire MDisk capacity is used.

-unit b | kb | mb | gb | tb | pb

(Optional) Specifies the data units to use with the capacity that is specified by the -size and -rsize parameters. The default unit type is MB.

-blocksize 512 | 4096

(Optional) Specifies the Small Computer System Interface (SCSI) Logical Unit sector size. The two possible values are 512 (the default) and 4096.

512 is the default. It is supported by all operating systems.
4096 provides better performance but it might not be supported by your host operating system or application.

-open_access_scsi_id vdisk_scsi_id

(Optional) Specifies the SCSI identifier to use when presenting the volume to a host when open access mode is enabled. This parameter defaults to the next incrementally available number starting from 0, and can be a value from 0 to 2047. The value must be unique across all volumes.

-name new_name_arg

(Optional) Specifies a name to assign to the new volume.

Description

This command creates a new volume object. You can use the command to create various types of volume objects, making it one of the most complex commands.

Remember: You can create a striped volume only in a child pool - you cannot create sequential or image volumes in a child pool.

You must decide which storage pool or storage pools provide the storage for the volume. Use the lsmdiskgrp command to list the available storage pools and the amount of free storage in each pool. If you are creating a volume with more than one copy, each storage pool that you specify must have enough space for the size of the volume.

If you create a thin-provisioned or compressed volume from a data reduction storage pool, that volume uses the same properties as the data reduction storage pool. You can create standard-provisioned volumes from data reduction pools, but these volumes use different data reduction properties.

A thin-provisioned or compressed volume that is in a data reduction storage pool must:

Not be in sequential or image mode.
Not have a warning threshold set (using -warning).
Use -cache readwrite when caching.
Have -autoexpand enabled.

For thin-provisioned and compressed volume copies that are in data reduction storage pools, the Easy Tier status is taken from the data reduction pool because that data is managed by a central data disk. It means that you cannot specify -easytier with thin-provisioned or compressed volumes.

Important: The extent size for the storage pool can limit volume size. Consider the maximum volume size that you want to use when you create storage pools. Refer to the information on creating storage pools for a comparison of the maximum volume capacity for each extent size. The maximum is different for thin-provisioned volumes.

No restriction exists for the number of compressed volumes within a data reduction storage pool.

Specify the virtualization type by using the -vtype parameter; the supported types are sequential (seq), striped, and image.

sequential (seq)

This virtualization type creates the volume that uses sequential extents from the specified MDisk (or MDisks, if creating multiple copies). The command fails if there are not enough sequential extents on the specified MDisk.

striped

The default virtualization type. If the -vtype parameter is not specified, striped is the default; all managed disks in the storage pool are used to create the volume. The striping is at an extent level; one extent from each managed disk in the group is used. For example, a storage pool with 10 managed disks uses one extent from each managed disk. It then uses the 11th extent from the first managed disk, and so on.

If the -mdisk parameter is also specified, you can supply a list of managed disks to use as the stripe set. It can be two or more managed disks from the same storage pool. The same circular algorithm is used across the striped set. However, a single managed disk can be specified more than once in the list. For example, if you enter -mdisk 0:1:2:1, the extents are from the following managed disks: 0, 1, 2, 1, 0, 1, 2, and so forth. All MDisks that are specified in the -mdisk parameter must be in the managed mode.

A capacity of 0 is allowed.

image

This virtualization type allows image mode volumes to be created when a managed disk already has data on it, perhaps from a previrtualized subsystem. When an image mode volume is created, it directly corresponds to the (previously unmanaged) managed disk that it was created from. Therefore, except for thin-provisioned image mode volumes, volume logical block address (LBA) x equals managed disk LBA x. You can use this command to bring a nonvirtualized disk under the control of the system. After it is under the control of the system, you can migrate the volume from the single managed disk. When it is migrated, the volume is no longer an image mode volume.

You can add image mode volumes to an already populated storage pool with other types of volumes, such as a striped or sequential.

Important: An image mode volume must be 512 bytes or greater. At least one extent is allocated to an image mode volume.

Remember: If you create a mirrored volume from two image mode MDisks without specifying a -size value, the capacity of the resulting volume is the smaller of the two MDisks, and the remaining space on the larger MDisk is not accessible.

Attention:

Do not create a volume in an offline I/O group. You must ensure that the I/O group is online before you create a volume to avoid any data loss. This action applies in particular to re-creating volumes that are assigned the same object ID.
To create an image mode disk, you must already have a quorum disk present in the system because an image mode disk cannot be used to hold quorum data. Refer to information on quorum disk creation for more details.
The command fails if either limit of 2048 volumes per I/O Group or 8192 volume copies per system is reached.

The rate at which the volume copies resynchronize after loss of synchronization can be specified by using the -syncrate parameter. This table provides the relationship of the syncrate value to the data copied per second.

Note: These settings also affect the initial rate of formatting.

Table 1. Relationship between the `syncrate` value and the amount of data copied per second
User-specified `syncrate` attribute value	Data copied per second
1 - 10	128 KB
11 - 20	256 KB
21 - 30	512 KB
31 - 40	1 MB
41 - 50	2 MB
51 - 60	4 MB
61 - 70	8 MB
71 - 80	16 MB
81 - 90	32 MB
91 - 100	64 MB
101 - 110	128 MB
111 - 120	256 MB
121 - 130	512 MB
131 - 140	1 GB
141 - 150	2 GB