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pvcreate

NAME

pvcreate - initialize a disk or partition for use by LVM

SYNOPSIS

pvcreate [-d|--debug] [-f[f]|--force [--force]] [-y|--yes] [-h|--help] [-t|--test] [-v|--verbose] [--labelsector] [-M|--metadatatypetype] [--[pv]metadatacopies#copies] [--metadatasizesize] [--metadataignorey|n] [--dataalignmentalignment] [--dataalignmentoffsetalignment_offset] [--restorefilefile] [--norestorefile] [--setphysicalvolumesizesize] [-u|--uuiduuid] [--version] [-Z|--zeroy|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.

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.

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 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)