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lvm2/man/lvreduce.8.in
Zdenek Kabelac 4fbde0143a Support rounding of percentage upward
We want to keep this logic -
when LV is extend - extend the LV by at least given amount,
when LV is reduced - reduce the LV by at most given amount.

So for this the rounding needs to be used.
Current logic which seems to satisfy give rule is to round up all
extent values for LV resize upward except for values with '-' sign
that are round downward.

This patch also fixes the problem when  lvextend --use-polices tried
to extend LV the by i.e. 20% - but the resulting 20% were smaller
the extent size thus before this patch no extension happened.
2012-01-05 15:38:18 +00:00

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Groff

.TH LVREDUCE 8 "LVM TOOLS #VERSION#" "Sistina Software UK" \" -*- nroff -*-
.SH NAME
lvreduce \- reduce the size of a logical volume
.SH SYNOPSIS
.B lvreduce
.RB [ \-A | \-\-autobackup
.RI { y | n }]
.RB [ \-d | \-\-debug ]
.RB [ \-h | \-\-help ]
.RB [ \-t | \-\-test ]
.RB [ \-v | \-\-verbose ]
.RB [ \-\-version ]
.RB [ \-f | \-\-force ]
.RB [ \-\-noudevsync ]
.RB { \-l | \-\-extents
.RI [ \- ] LogicalExtentsNumber [ % { VG | LV | FREE | ORIGIN "}] |"
.RB [ \-L | \-\-size
.RI [ \- ] LogicalVolumeSize [ bBsSkKmMgGtTpPeE ]}
.RB [ \-n | \-\-nofsck ]
.RB [ \-r | \-\-resizefs ]
.IR LogicalVolume { Name | Path }
.SH DESCRIPTION
lvreduce allows you to reduce the size of a logical volume.
Be careful when reducing a logical volume's size, because data in the
reduced part is lost!!!
.br
You should therefore ensure that any filesystem on the volume is
resized
.I before
running lvreduce so that the extents that are to be removed are not in use.
.br
Shrinking snapshot logical volumes (see
.BR lvcreate (8)
for information to create snapshots) is supported as well.
But to change the number of copies in a mirrored logical
volume use
.BR lvconvert (8).
.br
Sizes will be rounded if necessary - for example, the volume size must
be an exact number of extents and the size of a striped segment must
be a multiple of the number of stripes.
.br
.SH OPTIONS
See
.BR lvm (8)
for common options.
.TP
.BR \-f ", " \-\-force
Force size reduction without prompting even when it may cause data loss.
.TP
.BR \-\-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.
.TP
.IR \fB\-l ", " \fB\-\-extents " [" \- ] LogicalExtentsNumber [ % { VG | LV | FREE | ORIGIN }]
Reduce or set the logical volume size in units of logical extents.
With the \fI-\fP sign the value will be subtracted from
the logical volume's actual size and without it the value will be taken
as an absolute size.
The number can also be expressed as a percentage of the total space
in the Volume Group with the suffix \fI%VG\fP, relative to the existing
size of the Logical Volume with the suffix \fI%LV\fP, as a percentage of the
remaining free space in the Volume Group with the suffix \fI%FREE\fP, or (for
a snapshot) as a percentage of the total space in the Origin Logical
Volume with the suffix \fI%ORIGIN\fP.
The resulting value for the substraction is rounded downward, for the absolute
size it is rounded upward.
.TP
.IR \fB\-L ", " \fB\-\-size " [" \- ] LogicalVolumeSize [ bBsSkKmMgGtTpPeE ]
Reduce or set the logical volume size in units of megabytes.
A size suffix of \fIk\fP for kilobyte, \fIm\fP for megabyte,
\fIg\fP for gigabytes, \fIt\fP for terabytes, \fIp\fP for petabytes
or \fIe\fP for exabytes is optional.
With the \fI-\fP sign the value will be subtracted from
the logical volume's actual size and without it it will be taken as
an absolute size.
.TP
.BR \-n ", " \-\-nofsck
Do not perform fsck before resizing filesystem when filesystem
requires it. You may need to use \fB--force\fR to proceed with
this option.
.TP
.BR \-r ", " \-\-resizefs
Resize underlying filesystem together with the logical volume using
.BR fsadm (8).
.SH EXAMPLES
Reduce the size of logical volume lvol1 in volume group vg00 by 3 logical extents:
.sp
.B lvreduce -l -3 vg00/lvol1
.SH SEE ALSO
.BR fsadm (8),
.BR lvchange (8),
.BR lvconvert (8),
.BR lvcreate (8),
.BR lvextend (8),
.BR lvm (8),
.BR lvresize (8),
.BR vgreduce (8)