LVCONVERT(8)                                                  System Manager's Manual                                                 LVCONVERT(8)

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 cre-
              ates.

       --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.  activa-
              tion/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)

Red Hat, Inc                                             LVM TOOLS 2.02.95(2) (2012-03-06)                                            LVCONVERT(8)