table of contents
PVCREATE(8) | System Manager's Manual | PVCREATE(8) |
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 ...
[ -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:
[ -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.
--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
SEE ALSO¶
lvm(8), lvm.conf(5), lvmconfig(8), lvmdevices(8),
pvchange(8), pvck(8), pvcreate(8), pvdisplay(8), pvmove(8), pvremove(8), pvresize(8), pvs(8), pvscan(8),
vgcfgbackup(8), vgcfgrestore(8), vgchange(8), vgck(8), vgcreate(8), vgconvert(8), vgdisplay(8), vgexport(8), vgextend(8), vgimport(8), vgimportclone(8), vgimportdevices(8), vgmerge(8), vgmknodes(8), vgreduce(8), vgremove(8), vgrename(8), vgs(8), vgscan(8), vgsplit(8),
lvcreate(8), lvchange(8), lvconvert(8), lvdisplay(8), lvextend(8), lvreduce(8), lvremove(8), lvrename(8), lvresize(8), lvs(8), lvscan(8),
lvm-fullreport(8), lvm-lvpoll(8), lvm2-activation-generator(8), blkdeactivate(8), lvmdump(8),
dmeventd(8), lvmpolld(8), lvmlockd(8), lvmlockctl(8), cmirrord(8), lvmdbusd(8), fsadm(8),
lvmsystemid(7), lvmreport(7), lvmraid(7), lvmthin(7), lvmcache(7)
LVM TOOLS 2.03.14(2)-RHEL8 (2021-10-20) | Red Hat, Inc. |