mkvg

mkvg Command



Purpose

Creates a volume group.

Syntax

mkvg [ -d MaximumPhysicalVolumes ] [ -f ] [ -i ] [ -c ] 
[ -x ] [ -m MaxPvSize ] [ -n ] [ -s Size ] [ -V MajorNumber
] [ -y VolumeGroup ] PhysicalVolume ...

Description

The mkvg command creates a new volume group, using the physical volumes
represented by the PhysicalVolume parameter. After creating the volume
group, the mkvg command automatically varies on the new volume group
using the varyonvg command. The exception to this fact is when the
volume group is created with the -c option. When the volume group
is sucessfully created, the volume group will not be varied on automatically.
Instead, the user will be prompted to chose to varyon the volume group
in either the normal or Concurrent mode.

Notes: 

1.	The physical volume is checked to verify that it is not already
in another volume group. If the system believes the physical volume
belongs to a volume group that is varied on, it exits. But if the
system detects a description area from a volume group that is not
varied on, it prompts the user for confirmation in continuing with
the command. The previous contents of the physical volume are lost,
so the user must be cautious when using the override function.

2.	Before you attempt to add a new volume group, check the root file
system (with the df command) to ensure that 1 to 2MB of free space
exists. If you run the mkvg command on a full rootvg file system,
the mkvg command fails when it tries to vary on the newly created
volume group. If this occurs, create or free 2MB of space in the /etc
directory.

3.	To use this command,  either have root user authority or
be a member of the system group.

4.	For disks greater that 4GB, make sure that the Physical Partion
Size (-s) is set to a large enough value to utilize the entire disk.
The default value, 4MB, along with the maximum number of physical
partions (1016), will only utilize 4GB.

5.	After AIX Version 4.1, whenever you create a volume group, the
operating system automatically does a varyon. However if you create
a volume group with the -c flag, the system will not autovaryon the
volume group at the end of the Concurrent Capable volume group creation.
Instead, the mkvg command notifies you to manually varyonvg the volume
group in either non-concurrent or concurrent mode.

You can use the System Management Interface Tool (SMIT) fast path
to run this command. To use SMIT fast path, enter:

smit mkvg

Flags

-c	Creates a Concurrent Capable volume group. Only use the -c flag
with the HACMP. It has no effect on volume groups and systems not
using the HACMP product. This flag only applies to AIX Version 4.2
or later.

-d MaximumPhysicalVolumes	Estimates the maximum number of physical
volumes contained in the volume group. The default is 32; a smaller
number reduces physical volume space overhead.

-f	Forces the volume group to be created on the specified physical
volume unless the physical volume is part of another volume group
in the Device Configuration Database or a volume group that is active.

-i	Reads the PhysicalVolume parameter from standard input.

-m MaxPvSize	Specifies the maximum size of the physical volume. When
this flag is used, the number of physical partitions is calculated
based on the size of the physical volume. If this flag is not specified,
then 1016 physical partitions are assumed.

-n	Specifies that the volume group is not automatically available
during a system restart. The default value activates the volume group
automatically.

-s Size	Sets the number of megabytes in each physical partition, where
the Size variable is expressed in units of megabytes from 1 through
256. The Size variable must be equal to a power of 2 (example 1, 2,
4, 8). The default value is 4 megabytes.

-V MajorNumber	Specifies the major number of the volume group that
is created.

-x	Specifies to varyon automatically in Concurrent mode a Concurrent
Capable volume group set to varyon automatically during a system restart.
This flag has no meaning on systems which do not have the HACMP product
installed. This flag only applies to AIX Version 4.2 or later.

In order for this auto-varyon into concurrency of the volume group
to take effect,  enter the following line into the /etc/inittab
file:

rc_clvmv:2:wait:/usr/sbin/clvm_cfg 2>&1

Attention: This entry must be added after the entry used to initiate
srcmstr.

-y VolumeGroup	Specifies the volume group name rather than having
the name generated automatically. Volume group names must be unique
systemwide and can range from 1 to 15 characters. The name cannot
begin with a prefix already defined in the PdDv class in the Device
Configuration database for other devices. The volume group name created
is sent to standard output.

The volume group name can only contain the following characters: "A"
through "Z," "a" through "z," "0" through "9," or "_" (the underscore),
"-" (the minus sign), or "." (the period). All other characters are
considered invalid.

Examples

To create a volume group that contains three physical volumes with
partition size set to 1 megabyte, enter:

mkvg -s 1 hdisk3 hdisk5 hdisk6

The volume group is created with an automatically generated name,
which is displayed and available at system restart time.

Files

/etc	Directory where the mkvg command resides.

/tmp	Directory where the temporary files are stored while the command
is running.

/dev	Directory where the character device entry for the volume group
is created.

Related Information

The chvg command, lsvg command, varyonvg command.

The Logical Volume Storage Overview in AIX Version 4 System Management
Guide: Operating System and Devices.

The System Management Interface Tool (SMIT) Overview in AIX Version
4 System Management Guide: Operating System and Devices.

AIX HACMP/6000 Concepts and Facilities.