lvm2/man/vgcreate.8

.TH VGCREATE 8 "LVM TOOLS" "Sistina Software UK" \" -*- nroff -*-
.SH NAME
vgcreate \- create a volume group
.SH SYNOPSIS
.B vgcreate
.RB [ \-\-addtag
.IR Tag ]
.RB [ \-\-alloc 
.IR AllocationPolicy ]
.RB [ \-A | \-\-autobackup " {" y | n }]
.RB [ \-d | \-\-debug ]
.RB [ \-h | \-\-help ]
.RB [ \-l | \-\-maxlogicalvolumes
.IR MaxLogicalVolumes ]
.RB [ -M | \-\-metadatatype type]
.RB [ -p | \-\-maxphysicalvolumes
.IR MaxPhysicalVolumes ]
.RB [ \-s | \-\-physicalextentsize
.IR PhysicalExtentSize [ \fBkKmMgGtT\fR ]]
.RB [ \-t | \-\-test ]
.RB [ \-v | \-\-verbose ]
.RB [ \-\-version ]
.I VolumeGroupName PhysicalVolumePath
.RI [ PhysicalVolumePath ...]
.SH DESCRIPTION
.B vgcreate
creates a new volume group called
.I VolumeGroupName
using the block special device
.IR PhysicalVolumePath
previously configured for LVM with
.BR pvcreate (8).
.SH OPTIONS
See \fBlvm\fP for common options.
.TP
.BR \-l ", " \-\-maxlogicalvolumes " " \fIMaxLogicalVolumes\fR
Sets the maximum number of logical volumes allowed in this
volume group. 
The setting can be changed with \fBvgchange\fP.
For volume groups with metadata in lvm1 format, the limit
and default value is 255.  
If the metadata uses lvm2 format, the default value is 0
which removes this restriction: there is then no limit.
.TP
.BR \-p ", " \-\-maxphysicalvolumes " " \fIMaxPhysicalVolumes\fR
Sets the maximum number of physical volumes that can belong
to this volume group.
The setting can be changed with \fBvgchange\fP.
For volume groups with metadata in lvm1 format, the limit
and default value is 255.  
If the metadata uses lvm2 format, the default value is 0
which removes this restriction: there is then no limit.
If you have a large number of physical volumes in
a volume group with metadata in lvm2 format, 
for tool performance reasons, you should consider 
some use of \fB--metadatacopies 0\fP
as described in \fBpvcreate(8)\fP.
.TP
.BR \-s ", " \-\-physicalextentsize " " \fIPhysicalExtentSize\fR[\fBkKmMgGtT\fR]
Sets the physical extent size on physical volumes of this volume group.
A size suffix (k for kilobytes up to t for terabytes) is optional, megabytes
is the default if no suffix is present.  
The default is 4 MB and it must be at least 1 KB and a power of 2.

Once this value has been set, it is difficult to change it without recreating
the volume group which would involve backing up and restoring data on any 
logical volumes.  However, if no extents need moving for the new
value to apply, it can be altered using vgchange \-s.

If the volume group metadata uses lvm1 format, extents can vary in size from
8KB to 16GB and there is a limit of 65534 extents in each logical volume.  The
default of 4 MB leads to a maximum logical volume size of around 256GB.  

If the volume group metadata uses lvm2 format those restrictions do not apply,
but having a large number of extents will slow down the tools but have no
impact on I/O performance to the logical volume.  The smallest PE is 1KB.

The 2.4 kernel has a limitation of 2TB per block device.
.SH EXAMPLES
To create a volume group named
.B test_vg 
using physical volumes
.BR /dev/hdk1 ", and " /dev/hdl1
with default physical extent size of 4MB:
.nf

\	vgcreate test_vg /dev/sdk1 /dev/sdl1

.fi
.SH SEE ALSO
.BR lvm (8),
.BR pvdisplay (8),
.BR pvcreate (8),
.BR vgdisplay (8),
.BR vgextend (8),
.BR vgreduce (8),
.BR lvcreate (8),
.BR lvdisplay (8),
.BR lvextend (8),
.BR lvreduce (8)