Ubuntu Manpage: lvconvert - convert a logical volume from linear to mirror or snapshot

Provided by: lvm2_2.02.98-6ubuntu2_amd64

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   --thinpool   ThinPoolLogicalVolume{Name|Path}   [-c|--chunksize   ChunkSize]   [-h|-?|--help]
       [-v|--verbose] [--version] [-Z|--zero {y|n}] ThinMetadataLogicalVolume{Name|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(8) 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 4KiB and 512KiB.

-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(5), 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

       Converts the linear logical volume "vg00/lvol1" to a two-way mirror logical volume:

       lvconvert -m1 vg00/lvol1

       Converts the linear logical volume "vg00/lvol1" to a two-way RAID1 logical volume:

       lvconvert --type raid1 -m1 vg00/lvol1

       Converts a mirror with a disk log to a mirror with an in-memory log:

       lvconvert --mirrorlog core vg00/lvol1

       Converts a mirror with an in-memory log to a mirror with a disk log:

       lvconvert --mirrorlog disk vg00/lvol1

       Converts a mirror logical volume to a linear logical volume:

       lvconvert -m0 vg00/lvol1

       Converts a mirror logical volume to a RAID1 logical volume with the same number of images:

       lvconvert --type raid1 vg00/mirror_lv

       Converts logical volume "vg00/lvol2" to snapshot of original volume "vg00/lvol1":

       lvconvert -s vg00/lvol1 vg00/lvol2

       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 -m1 vg00/lvol1 /dev/sda:0-15 /dev/sdb:0-15

       Converts mirror logical volume "vg00/lvmirror1" to linear, freeing physical extents from /dev/sda:

       lvconvert -m0 vg00/lvmirror1 /dev/sda

       Merges "vg00/lvol1_snap" into its origin:

       lvconvert --merge vg00/lvol1_snap

       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 --merge @some_tag

       Extracts 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 --name lv_split vg00/lvmirror1

       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 --splitmirrors 1 --trackchanges vg00/lv_raid1

       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 --merge vg00/lv_raid1_rimage_1

       Replaces  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.

       lvconvert --replace /dev/sdb1 vg00/my_raid1 /dev/sdf1

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

Examples

SEE ALSO