update reworded string

[lvm2.git] / man / pvcreate.8.in

.TH PVCREATE 8 "LVM TOOLS #VERSION#" "Sistina Software UK" \" -*- nroff -*-
.SH NAME
pvcreate \- initialize a disk or partition for use by LVM
.SH SYNOPSIS
.B pvcreate
.RB [ \-d | \-\-debug ]
.RB [ \-h | \-\-help ]
.RB [ \-t | \-\-test ]
.RB [ \-v | \-\-verbose ]
.RB [ \-\-version ]
.RB [ \-f [ f ]| \-\-force " [" \-\-force ]]
.RB [ \-y | \-\-yes ]
.RB [ \-\-labelsector ]
.RB [ \-M | \-\-metadatatype " " \fItype ]
.RB [ \-\-[pv]metadatacopies " " \fI#copies ]
.RB [ \-\-metadatasize " " \fIsize ]
.RB [ \-\-metadataignore " {" \fIy | \fIn }]
.RB [ \-\-dataalignment " " \fIalignment ]
.RB [ \-\-dataalignmentoffset " " \fIalignment_offset ]
.RB [ \-\-restorefile " " \fIfile ]
.RB [ \-\-norestorefile ]
.RB [ \-\-setphysicalvolumesize " " \fIsize ]
.RB [ \-u | \-\-uuid " " \fIuuid ]
.RB [ \-Z | \-\-zero " {" \fIy | \fIn }]
.IR PhysicalVolume " [" PhysicalVolume ...]
.SH DESCRIPTION
.B pvcreate
initializes
.I PhysicalVolume
for later use by the Logical Volume Manager (LVM).  Each
.I PhysicalVolume
can be a disk partition, whole disk, meta device, or loopback file.
For DOS disk partitions, the partition id should be set to 0x8e using
.BR fdisk "(8), " cfdisk "(8), "
or a equivalent.  For
.B whole disk devices only
the partition table must be erased, which will effectively destroy all
data on that disk.  This can be done by zeroing the first sector with:
.sp
.BI "dd if=/dev/zero of=" PhysicalVolume " bs=512 count=1"
.sp
Continue with
.BR vgcreate (8)
to create a new volume group on
.IR PhysicalVolume ,
or
.BR vgextend (8)
to add
.I PhysicalVolume
to an existing volume group.
.SH OPTIONS
See \fBlvm\fP(8) for common options.
.TP
.BR \-f ", " \-\-force
Force the creation without any confirmation.  You can not recreate
(reinitialize) a physical volume belonging to an existing volume group.
In an emergency you can override this behaviour with \fB-ff\fP.
.TP
.BR \-u ", " \-\-uuid " " \fIuuid
Specify the uuid for the device.  
Without this option, \fBpvcreate\fP generates a random uuid.
All of your physical volumes must have unique uuids.
You need to use this option before restoring a backup of LVM metadata 
onto a replacement device - see \fBvgcfgrestore\fP(8).  As such, use of
\fB--restorefile\fP is compulsory unless the \fB--norestorefile\fP is
used.
.TP
.BR \-y ", " \-\-yes
Answer yes to all questions.
.TP
.BR \-Z ", " \-\-zero " " \fIy | \fIn
Whether or not the first 4 sectors (2048 bytes) of the device should be 
wiped.
If this option is not given, the 
default is to wipe these sectors unless either or both of the \fB--restorefile\fP
or \fB--uuid\fP options were specified.
.SH NEW METADATA OPTIONS
LVM2 introduces a new format for storing metadata on disk.
This new format is more efficient and resilient than the format the 
original version of LVM used and offers the advanced user greater 
flexibility and control.
.sp
The new format may be selected on the command line with \fB-M2\fP or by 
setting \fBformat = "lvm2"\fP in the \fBglobal\fP section of \fBlvm.conf\fP.
Each physical volume in the same volume group must use the same format, but
different volume groups on a machine may use different formats 
simultaneously: the tools can handle both formats.
Additional formats can be added as shared libraries.
.sp
Additional tools for manipulating the locations and sizes of metadata areas 
will be written in due course.  Use the verbose/debug options on the tools
to see where the metadata areas are placed.
.TP
.BI \-\-metadatasize " size"
The approximate amount of space to be set aside for each metadata area.
(The size you specify may get rounded.)
.TP
.BI \-\-dataalignment " alignment"
Align the start of the data to a multiple of this number.
You should also specify an appropriate \fIPhysicalExtentSize\fP when creating
the Volume Group with \fBvgcreate\fP.
.sp
To see the location of the first Physical Extent of an existing Physical Volume
use \fBpvs -o +pe_start\fP .  It will be a multiple of the requested
alignment.  In addition it may be shifted by \fIalignment_offset\fP from
\fIdata_alignment_offset_detection\fP (if enabled in \fBlvm.conf\fP) or
\fB--dataalignmentoffset\fP.
.TP
.BI \-\-dataalignmentoffset " alignment_offset"
Shift the start of the data area by this additional \fIalignment_offset\fP.
.TP
.BI \-\-[pv]metadatacopies " copies"
The number of metadata areas to set aside on each PV.  Currently
this can be 0, 1 or 2.  
If set to 2, two copies of the volume group metadata 
are held on the PV, one at the front of the PV and one at the end.  
If set to 1 (the default), one copy is kept at the front of the PV 
(starting in the 5th sector).
If set to 0, no copies are kept on this PV - you might wish to use this
with VGs containing large numbers of PVs.  But if you do this and
then later use \fBvgsplit\fP you must ensure that each VG is still going 
to have a suitable number of copies of the metadata after the split!
.TP
.BI \-\-metadataignore " y" \fR| n
Ignore or un-ignore metadata areas on this physical volume.
The default is "n".  This setting can be changed with \fBpvchange\fP.
If metadata areas on a physical volume are ignored, LVM will
not store metadata in the metadata areas present on this Physical
Volume.  Metadata areas cannot be created or extended after Logical
Volumes have been allocated on the device. If you do not want to store
metadata on this device, it is still wise always to allocate a metadata
area in case you need it in the future and to use this option to instruct
LVM2 to ignore it.
.TP
.BI \-\-restorefile " file"
In conjunction with \fB--uuid\fP, this extracts the location and size
of the data on the PV from the file (produced by \fBvgcfgbackup\fP)
and ensures that the metadata that the program produces is consistent 
with the contents of the file i.e. the physical extents will be in 
the same place and not get overwritten by new metadata.  This provides
a mechanism to upgrade the metadata format or to add/remove metadata
areas. Use with care. See also \fBvgconvert\fP(8).
.TP
.B \-\-norestorefile
In conjunction with \fB--uuid\fP, this allows a \fIuuid\fP to be specified
without also requiring that a backup of the metadata be provided.
.TP
.BI \-\-labelsector " sector"
By default the PV is labelled with an LVM2 identifier in its second 
sector (sector 1).  This lets you use a different sector near the
start of the disk (between 0 and 3 inclusive - see LABEL_SCAN_SECTORS
in the source).  Use with care.
.TP
.BI \-\-setphysicalvolumesize " size"
Overrides the automatically-detected size of the PV.  Use with care.
.SH EXAMPLES
Initialize partition #4 on the third SCSI disk and the entire fifth
SCSI disk for later use by LVM:
.sp
.B pvcreate /dev/sdc4 /dev/sde
.sp
If the 2nd SCSI disk is a 4KB sector drive that compensates for windows
partitioning (sector 7 is the lowest aligned logical block, the 4KB
sectors start at LBA -1, and consequently sector 63 is aligned on a 4KB
boundary) manually account for this when initializing for use by LVM:
.sp
.B pvcreate --dataalignmentoffset 7s /dev/sdb
.sp
.SH SEE ALSO
.BR lvm.conf (5),
.BR lvm (8),
.BR vgcreate (8), 
.BR vgextend (8), 
.BR lvcreate (8), 
.BR cfdisk (8), 
.BR fdisk (8), 
.BR losetup (8), 
.BR mdadm (8), 
.BR vgcfgrestore (8), 
.BR vgconvert (8)