Ubuntu Manpage: pvcreate — Initialize physical volume(s) for use by LVM

Provided by: lvm2_2.03.16-1ubuntu1_amd64

NAME

       pvcreate — Initialize physical volume(s) for use by LVM

SYNOPSIS

       pvcreate position_args
           [ option_args ]

DESCRIPTION

pvcreate initializes a Physical Volume (PV) on a device so the device is recognized as
belonging to LVM. This allows the PV to be used in a Volume Group (VG). An LVM disk
label is written to the device, and LVM metadata areas are initialized. A PV can be
placed on a whole device or partition.

Use vgcreate(8) to create a new VG on the PV, or vgextend(8) to add the PV to an existing
VG. Use pvremove(8) to remove the LVM disk label from the device.

The force option will create a PV without confirmation. Repeating the force option (-ff)
will forcibly create a PV, overriding checks that normally prevent it, e.g. if the PV is
already in a VG.

Metadata location, size, and alignment

The LVM disk label begins 512 bytes from the start of the device, and is 512 bytes in
size.

The LVM metadata area begins at an offset (from the start of the device) equal to the page
size of the machine creating the PV (often 4 KiB.) The metadata area contains a 512 byte
header and a multi-KiB circular buffer that holds text copies of the VG metadata.

With default settings, the first physical extent (PE), which contains LV data, is 1 MiB
from the start of the device. This location is controlled by default_data_alignment in
lvm.conf, which is set to 1 (MiB) by default. The pe_start will be a multiple of this
many MiB. This location can be checked with:
pvs -o pe_start PV

The size of the LVM metadata area is the space between the the start of the metadata area
and the first PE. When metadata begins at 4 KiB and the first PE is at 1024 KiB, the
metadata area size is 1020 KiB. This can be checked with:
pvs -o mda_size PV

The mda_size cannot be increased after pvcreate, so if larger metadata is needed, it must
be set during pvcreate. Two copies of the VG metadata must always fit within the metadata
area, so the maximum VG metadata size is around half the mda_size. This can be checked
with:
vgs -o mda_free VG

A larger metadata area can be set with --metadatasize. The resulting mda_size may be
larger than specified due to default_data_alignment placing pe_start on a MiB boundary,
and the fact that the metadata area extends to the first PE. With metadata starting at 4
KiB and default_data_alignment 1 (MiB), setting --metadatasize 2048k results in pe_start
of 3 MiB and mda_size of 3068 KiB. Alternatively, --metadatasize 2044k results in
pe_start at 2 MiB and mda_size of 2044 KiB.

The alignment of pe_start described above may be automatically overridden based on md
device properties or device i/o properties reported in sysfs. These automatic adjustments
can be enabled/disabled using lvm.conf settings md_chunk_alignment and
data_alignment_offset_detection.

To use a different pe_start alignment, use the --dataalignment option. The --metadatasize
option would also typically be used in this case because the metadata area size also
determines the location of pe_start. When using these two options together, pe_start is
calculated as: metadata area start (page size), plus the specified --metadatasize, rounded
up to the next multiple of --dataalignment. With metadata starting at 4 KiB,
--metadatasize 2048k, and --dataalignment 128k, pe_start is 2176 KiB and mda_size is 2172
KiB. The pe_start of 2176 KiB is the nearest even multiple of 128 KiB that provides at
least 2048 KiB of metadata space. Always check the resulting alignment and metadata size
when using these options.

To shift an aligned pe_start value, use the --dataalignmentoffset option. The pe_start
alignment is calculated as described above, and then the value specified with
--dataalignmentoffset is added to produce the final pe_start value.

USAGE

       pvcreate PV ...
           [ -f|--force ]
           [ -M|--metadatatype lvm2 ]
           [ -u|--uuid String ]
           [ -Z|--zero y|n ]
           [    --dataalignment Size[k|UNIT] ]
           [    --dataalignmentoffset Size[k|UNIT] ]
           [    --bootloaderareasize Size[m|UNIT] ]
           [    --labelsector Number ]
           [    --[pv]metadatacopies 0|1|2 ]
           [    --metadatasize Size[m|UNIT] ]
           [    --metadataignore y|n ]
           [    --norestorefile ]
           [    --setphysicalvolumesize Size[m|UNIT] ]
           [    --reportformat basic|json ]
           [    --restorefile String ]
           [ COMMON_OPTIONS ]

       Common options for lvm:
           [ -d|--debug ]
           [ -h|--help ]
           [ -q|--quiet ]
           [ -t|--test ]
           [ -v|--verbose ]
           [ -y|--yes ]
           [    --commandprofile String ]
           [    --config String ]
           [    --devices PV ]
           [    --devicesfile String ]
           [    --driverloaded y|n ]
           [    --journal String ]
           [    --lockopt String ]
           [    --longhelp ]
           [    --nohints ]
           [    --nolocking ]
           [    --profile String ]
           [    --version ]

OPTIONS

--bootloaderareasize Size[m|UNIT]
Reserve space for the bootloader between the LVM metadata area and the first PE.
The bootloader area is reserved for bootloaders to embed their own data or
metadata; LVM will not use it. The bootloader area begins where the first PE would
otherwise be located. The first PE is moved out by the size of the bootloader
area, and then moved out further if necessary to match the data alignment. The
start of the bootloader area is always aligned, see also --dataalignment and
--dataalignmentoffset. The bootloader area may be larger than requested due to the
alignment, but it's never less than the requested size. To see the bootloader area
start and size of an existing PV use pvs -o +pv_ba_start,pv_ba_size.

--commandprofile String
The command profile to use for command configuration. See lvm.conf(5) for more
information about profiles.

--config String
Config settings for the command. These override lvm.conf(5) settings. The String
arg uses the same format as lvm.conf(5), or may use section/field syntax. See
lvm.conf(5) for more information about config.

--dataalignment Size[k|UNIT]
Align the start of a PV data area with a multiple of this number. To see the
location of the first Physical Extent (PE) of an existing PV, use pvs -o +pe_start.
In addition, it may be shifted by an alignment offset, see --dataalignmentoffset.
Also specify an appropriate PE size when creating a VG.

--dataalignmentoffset Size[k|UNIT]
Shift the start of the PV data area by this additional offset.

-d|--debug ...
Set debug level. Repeat from 1 to 6 times to increase the detail of messages sent
to the log file and/or syslog (if configured).

--devices PV
Restricts the devices that are visible and accessible to the command. Devices not
listed will appear to be missing. This option can be repeated, or accepts a comma
separated list of devices. This overrides the devices file.

--devicesfile String
A file listing devices that LVM should use. The file must exist in
/etc/lvm/devices/ and is managed with the lvmdevices(8) command. This overrides
the lvm.conf(5) devices/devicesfile and devices/use_devicesfile settings.

--driverloaded y|n
If set to no, the command will not attempt to use device-mapper. For testing and
debugging.

-f|--force ...
Override various checks, confirmations and protections. Use with extreme caution.

-h|--help
Display help text.

--journal String
Record information in the systemd journal. This information is in addition to
information enabled by the lvm.conf log/journal setting. command: record
information about the command. output: record the default command output. debug:
record full command debugging.

--labelsector Number
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.

--lockopt String
Used to pass options for special cases to lvmlockd. See lvmlockd(8) for more
information.

--longhelp
Display long help text.

--metadataignore y|n
Specifies the metadataignore property of a PV. If yes, metadata areas on the PV
are ignored, and lvm will not store metadata in the metadata areas of the PV. If
no, lvm will store metadata on the PV.

--metadatasize Size[m|UNIT]
The approximate amount of space used for each VG metadata area. The size may be
rounded.

-M|--metadatatype lvm2
Specifies the type of on-disk metadata to use. lvm2 (or just 2) is the current,
standard format. lvm1 (or just 1) is no longer used.

--nohints
Do not use the hints file to locate devices for PVs. A command may read more
devices to find PVs when hints are not used. The command will still perform
standard hint file invalidation where appropriate.

--nolocking
Disable locking. Use with caution, concurrent commands may produce incorrect
results.

--norestorefile
In conjunction with --uuid, this allows a uuid to be specified without also
requiring that a backup of the metadata be provided.

--profile String
An alias for --commandprofile or --metadataprofile, depending on the command.

--[pv]metadatacopies 0|1|2
The number of metadata areas to set aside on a PV for storing VG metadata. When 2,
one copy of the VG metadata is stored at the front of the PV and a second copy is
stored at the end. When 1, one copy of the VG metadata is stored at the front of
the PV. When 0, no copies of the VG metadata are stored on the given PV. This may
be useful in VGs containing many PVs (this places limitations on the ability to use
vgsplit later.)

-q|--quiet ...
Suppress output and log messages. Overrides --debug and --verbose. Repeat once to
also suppress any prompts with answer 'no'.

--reportformat basic|json
Overrides current output format for reports which is defined globally by the
report/output_format setting in lvm.conf(5). basic is the original format with
columns and rows. If there is more than one report per command, each report is
prefixed with the report name for identification. json produces report output in
JSON format. See lvmreport(7) for more information.

--restorefile String
In conjunction with --uuid, this reads the file (produced by vgcfgbackup), extracts
the location and size of the data on the PV, and ensures that the metadata produced
by the program is consistent with the contents of the file, i.e. the physical
extents will be in the same place and not be overwritten by new metadata. This
provides a mechanism to upgrade the metadata format or to add/remove metadata
areas. Use with care.

--setphysicalvolumesize Size[m|UNIT]
Overrides the automatically detected size of the PV. Use with care, or prior to
reducing the physical size of the device.

-t|--test
Run in test mode. Commands will not update metadata. This is implemented by
disabling all metadata writing but nevertheless returning success to the calling
function. This may lead to unusual error messages in multi-stage operations if a
tool relies on reading back metadata it believes has changed but hasn't.

-u|--uuid String
Specify a UUID for the device. Without this option, a random UUID is generated.
This option is needed 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. All PVs must have unique UUIDs, and LVM will prevent
certain operations if multiple devices are seen with the same UUID. See
vgimportclone(8) for more information.

-v|--verbose ...
Set verbose level. Repeat from 1 to 4 times to increase the detail of messages sent
to stdout and stderr.

--version
Display version information.

-y|--yes
Do not prompt for confirmation interactively but always assume the answer yes. Use
with extreme caution. (For automatic no, see -qq.)

-Z|--zero y|n
Controls if the first 4 sectors (2048 bytes) of the device are wiped. The default
is to wipe these sectors unless either or both of --restorefile or --uuid are
specified.

VARIABLES

       PV     Physical Volume name, a device path under /dev.   For  commands  managing  physical
              extents,  a  PV  positional  arg  generally accepts a suffix indicating a range (or
              multiple ranges) of physical extents (PEs).  When  the  first  PE  is  omitted,  it
              defaults to the start of the device, and when the last PE is omitted it defaults to
              end.  Start and end  range  (inclusive):  PV[:PE-PE]...   Start  and  length  range
              (counting from 0): PV[:PE+PE]...

       String See the option description for information about the string content.

       Size[UNIT]
              Size  is  an  input  number  that accepts an optional unit.  Input units are always
              treated as base two values, regardless of capitalization, e.g.  'k'  and  'K'  both
              refer  to  1024.  The default input unit is specified by letter, followed by |UNIT.
              UNIT represents other possible input units: b|B is bytes, s|S  is  sectors  of  512
              bytes,  k|K  is  KiB,  m|M  is MiB, g|G is GiB, t|T is TiB, p|P is PiB, e|E is EiB.
              (This should not be confused with the output control --units, where capital letters
              mean multiple of 1000.)

ENVIRONMENT VARIABLES

       See  lvm(8)  for  information  about  environment  variables  used  by  lvm.  For example,
       LVM_VG_NAME can generally be substituted for a required VG parameter.

EXAMPLES

       Initialize a partition and a full device.
       pvcreate /dev/sdc4 /dev/sde

       If a device is a 4KiB sector drive that compensates for windows partitioning (sector 7  is
       the  lowest  aligned  logical  block,  the  4KiB sectors start at LBA -1, and consequently
       sector 63 is aligned on a 4KiB boundary) manually account for this when  initializing  for
       use by LVM.
       pvcreate --dataalignmentoffset 7s /dev/sdb