NAME¶
lvconvert - convert a logical volume from linear to mirror or snapshot
SYNOPSIS¶
lvconvert -m|--mirrors Mirrors [--mirrorlog {disk|core|mirrored}]
[--corelog] [-R|--regionsize MirrorLogRegionSize] [--type SegmentType]
[-A|--alloc AllocationPolicy] [-b|--background] [-f|--force] [-i|--interval
Seconds] [-h|-?|--help] [--stripes Stripes [-I|--stripesize StripeSize]]
[--noudevsync] [-v|--verbose] [-y|--yes] [--version]
LogicalVolume[Path] [PhysicalVolume[Path][:PE[-PE]]...]
lvconvert --splitmirrors Images [--name SplitLogicalVolumeName]
[--trackchanges]
MirrorLogicalVolume[Path] [SplittablePhysicalVolume[Path][:PE[-PE]]...]
lvconvert -s|--snapshot [-c|--chunksize ChunkSize] [-h|-?|--help]
[--noudevsync] [-v|--verbose] [-Z|--zero y|n] [--version]
OriginalLogicalVolume[Path] SnapshotLogicalVolume[Path]
lvconvert --merge [-b|--background] [-i|--interval Seconds]
[-h|-?|--help] [-v|--verbose] [--version] LogicalVolume[Path]...
lvconvert --repair [-h|-?|--help] [-v|--verbose] [--version]
LogicalVolume[Path] [PhysicalVolume[Path]...]
lvconvert --replace PhysicalVolume [-h|-?|--help] [-v|--verbose]
[--version] LogicalVolume[Path] [PhysicalVolume[Path]...]
DESCRIPTION¶
lvconvert is used to change the segment type (i.e. linear, mirror, etc) or
characteristics of a logical volume. For example, it can add or remove the
redundant images of a logical volume, change the log type of a mirror, or
designate a logical volume as a snapshot repository.
If the conversion requires allocation of physical extents (for example, when
converting from linear to mirror) and you specify one or more PhysicalVolumes
(optionally with ranges of physical extents), allocation of physical extents
will be restricted to these physical extents. If the conversion frees physical
extents (for example, when converting from a mirror to a linear, or reducing
mirror legs) and you specify one or more PhysicalVolumes, the freed extents
come first from the specified PhysicalVolumes.
OPTIONS¶
See
lvm for common options.
Exactly one of --splitmirrors, --mirrors, --repair, --snapshot or --merge
arguments is required.
- -m, --mirrors Mirrors
- Specifies the degree of the mirror you wish to create. For
example, "-m 1" would convert the original logical volume to a
mirror volume with 2-sides; that is, a linear volume plus one copy.
- --mirrorlog {disk|core|mirrored}
- Specifies the type of log to use. The default is disk,
which is persistent and requires a small amount of storage space, usually
on a separate device from the data being mirrored. Core may be useful for
short-lived mirrors: It means the mirror is regenerated by copying the
data from the first device again every time the device is activated -
perhaps, for example, after every reboot. Using "mirrored" will
create a persistent log that is itself mirrored.
- --corelog
- The optional argument "--corelog" is the same as
specifying "--mirrorlog core".
- -R, --regionsize MirrorLogRegionSize
- A mirror is divided into regions of this size (in MB), and
the mirror log uses this granularity to track which regions are in
sync.
- --type SegmentType
- Used to convert a logical volume to another segment type or
to explicitly state the desired RAID1 segment type ("mirror" or
"raid1") when converting a linear logical volume to a mirror
with the '-m' argument.
- -b, --background
- Run the daemon in the background.
- -i, --interval Seconds
- Report progress as a percentage at regular intervals.
- --noudevsync
- Disable udev synchronisation. The process will not wait for
notification from udev. It will continue irrespective of any possible udev
processing in the background. You should only use this if udev is not
running or has rules that ignore the devices LVM2 creates.
- --splitmirrors Images
- The number of redundant Images of a mirror to be split off
and used to form a new logical volume. A name must be supplied for the
newly-split-off logical volume using the --name argument, unless the
--trackchanges argument is given.
- -n Name
- The name to apply to a logical volume which has been split
off from a mirror logical volume.
- --trackchanges
- Used with --splitmirrors on a raid1 device, this tracks
changes so that the read-only detached image can be merged efficiently
back into the mirror later. Only the regions of the detatched device where
the data changed get resynchronized.
Please note that this feature is only supported with the new md-based mirror
implementation and not with the original device-mapper mirror
implementation.
- -s, --snapshot
- Create a snapshot from existing logical volume using
another existing logical volume as its origin.
- -c, --chunksize ChunkSize
- Power of 2 chunk size for the snapshot logical volume
between 4k and 512k.
- -Z, --zero y|n
- Controls zeroing of the first KB of data in the snapshot.
If the volume is read-only the snapshot will not be zeroed.
- --merge
- Merges a snapshot into its origin volume or merges a raid1
image that has been split from its mirror with --trackchanges back into
its mirror.
To check if your kernel supports the snapshot merge feature, look for
'snapshot-merge' in the output of 'dmsetup targets'. If both the origin
and snapshot volume are not open the merge will start immediately.
Otherwise, the merge will start the first time either the origin or
snapshot are activated and both are closed. Merging a snapshot into an
origin that cannot be closed, for example a root filesystem, is deferred
until the next time the origin volume is activated. When merging starts,
the resulting logical volume will have the origin's name, minor number and
UUID. While the merge is in progress, reads or writes to the origin appear
as they were directed to the snapshot being merged. When the merge
finishes, the merged snapshot is removed. Multiple snapshots may be
specified on the commandline or a @tag may be used to specify multiple
snapshots be merged to their respective origin.
- --repair
- Repair a mirror after suffering a disk failure. The mirror
will be brought back into a consistent state. By default, the original
number of mirrors will be restored if possible. Specify -y on the command
line to skip the prompts. Use -f if you do not want any replacement.
Additionally, you may use --use-policies to use the device replacement
policy specified in lvm.conf, viz. activation/mirror_log_fault_policy or
activation/mirror_device_fault_policy.
- --replace PhysicalVolume
- Remove the specified device (PhysicalVolume) and replace it
with one that is available in the volume group or from the specific list
provided. This option is only available to RAID segment types (e.g.
"raid1", "raid5", etc).
Examples¶
"lvconvert -m1 vg00/lvol1"
converts the linear logical volume "vg00/lvol1" to a two-way mirror
logical volume.
Examples¶
"lvconvert --type raid1 -m1 vg00/lvol1"
converts the linear logical volume "vg00/lvol1" to a two-way RAID1
logical volume.
"lvconvert --mirrorlog core vg00/lvol1"
converts a mirror with a disk log to a mirror with an in-memory log.
"lvconvert --mirrorlog disk vg00/lvol1"
converts a mirror with an in-memory log to a mirror with a disk log.
"lvconvert -m0 vg00/lvol1"
converts a mirror logical volume to a linear logical volume.
"lvconvert --type raid1 vg00/mirror_lv"
converts a mirror logical volume to a RAID1 logical volume with the same number
of images.
"lvconvert -s vg00/lvol1 vg00/lvol2"
converts logical volume "vg00/lvol2" to snapshot of original volume
"vg00/lvol1"
"lvconvert -m1 vg00/lvol1 /dev/sda:0-15 /dev/sdb:0-15"
converts linear logical volume "vg00/lvol1" to a two-way mirror, using
physical extents /dev/sda:0-15 and /dev/sdb:0-15 for allocation of new
extents.
"lvconvert -m0 vg00/lvmirror1 /dev/sda"
converts mirror logical volume "vg00/lvmirror1" to linear, freeing
physical extents from /dev/sda.
"lvconvert --merge vg00/lvol1_snap"
merges "vg00/lvol1_snap" into its origin.
"lvconvert --merge @some_tag"
If vg00/lvol1, vg00/lvol2, and vg00/lvol3 are all tagged with
"some_tag" each snapshot logical volume will be merged serially,
e.g.: vg00/lvol1, then vg00/lvol2, then vg00/lvol3. If --background were used
it would start all snapshot logical volume merges in parallel.
"lvconvert --splitmirrors 1 --name lv_split vg00/lvmirror1"
Extract one image from the mirror, making it a new logical volume named
"lv_split". The mirror the image is extracted from is reduced
accordingly. If it was a 2-way mirror (created with '-m 1'), then the
resulting original volume will be linear.
"lvconvert --splitmirrors 1 --trackchanges vg00/lv_raid1"
A mirrored logical volume created with --type raid1 can use the '--trackchanges'
argument when splitting off an image.
Detach one image from the mirrored logical volume lv_raid1 as a separate
read-only device and track the changes made to the mirror while it is
detached. The split-off device has a name of the form lv_raid1_rimage_N, where
N is a number, and it cannot be renamed.
"lvconvert --merge vg00/lv_raid1_rimage_1"
Merge an image that was detached temporarily from its mirror with the
'--trackchanges' argument back into its original mirror and bring its contents
back up-to-date.
"lvconvert --replace /dev/sdb1 vg00/my_raid1 /dev/sdf1"
Replace the physical volume "/dev/sdb1" in the RAID1 logical volume
"my_raid1" with the specified physical volume "/dev/sdf1".
Had the argument "/dev/sdf1" been left out, lvconvert would attempt
to find a suitable device from those available in the volume group.
SEE ALSO¶
lvm(8),
vgcreate(8),
lvremove(8),
lvrename(8),
lvextend(8),
lvreduce(8),
lvdisplay(8),
lvscan(8)