NAME¶
pvcreate - initialize a disk or partition for use by LVM
SYNOPSIS¶
pvcreate [
-d|
--debug] [
-h|
--help]
[
-t|
--test] [
-v|
--verbose] [
--version]
[
-f[
f]|
--force [
--force]] [
-y|
--yes]
[
--labelsector] [
-M|
--metadatatype
type] [
--[pv]metadatacopies
#copies] [
--metadatasize
size] [
--metadataignore
{
y|n}]
[
--dataalignment alignment]
[
--dataalignmentoffset alignment_offset]
[
--restorefile file] [
--norestorefile]
[
--setphysicalvolumesize size]
[
-u|
--uuid uuid] [
-Z|
--zero
{
y|n}] PhysicalVolume
[
PhysicalVolume...]
DESCRIPTION¶
pvcreate initializes
PhysicalVolume for later use by the Logical
Volume Manager (LVM). Each
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
fdisk(8),
cfdisk(8), or
a equivalent. For
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:
dd if=/dev/zero of=PhysicalVolume bs=512 count=1
Continue with
vgcreate(8) to create a new volume group on
PhysicalVolume, or
vgextend(8) to add
PhysicalVolume to
an existing volume group.
OPTIONS¶
See
lvm(8) for common options.
- -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
-ff.
- -u, --uuid uuid
- Specify the uuid for the device. Without this option,
pvcreate 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 vgcfgrestore(8). As
such, use of --restorefile is compulsory unless the
--norestorefile is used.
- -y, --yes
- Answer yes to all questions.
- -Z, --zero
y|n
- 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 --restorefile or
--uuid options were specified.
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.
The new format may be selected on the command line with
-M2 or by setting
format = "lvm2" in the
global section of
lvm.conf. 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.
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.
- --metadatasize size
- The approximate amount of space to be set aside for each
metadata area. (The size you specify may get rounded.)
- --dataalignment alignment
- Align the start of the data to a multiple of this number.
You should also specify an appropriate PhysicalExtentSize when
creating the Volume Group with vgcreate.
To see the location of the first Physical Extent of an existing Physical
Volume use pvs -o +pe_start . It will be a multiple of the
requested alignment. In addition it may be shifted by
alignment_offset from data_alignment_offset_detection (if
enabled in lvm.conf) or --dataalignmentoffset.
- --dataalignmentoffset alignment_offset
- Shift the start of the data area by this additional
alignment_offset.
- --[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 vgsplit you must ensure that
each VG is still going to have a suitable number of copies of the metadata
after the split!
- --metadataignore y|n
- Ignore or un-ignore metadata areas on this physical volume.
The default is "n". This setting can be changed with
pvchange. 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.
- --restorefile file
- In conjunction with --uuid, this extracts the
location and size of the data on the PV from the file (produced by
vgcfgbackup) 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 vgconvert(8).
- --norestorefile
- In conjunction with --uuid, this allows a
uuid to be specified without also requiring that a backup of the
metadata be provided.
- --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.
- --setphysicalvolumesize size
- Overrides the automatically-detected size of the PV. Use
with care.
EXAMPLES¶
Initialize partition #4 on the third SCSI disk and the entire fifth SCSI disk
for later use by LVM:
pvcreate /dev/sdc4 /dev/sde
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:
pvcreate --dataalignmentoffset 7s /dev/sdb
SEE ALSO¶
lvm.conf(5),
lvm(8),
vgcreate(8),
vgextend(8),
lvcreate(8),
cfdisk(8),
fdisk(8),
losetup(8),
mdadm(8),
vgcfgrestore(8),
vgconvert(8)