Centos 7 Reallocate logical volume space to another

Do you hate how Centos 7 defaults to allocating most of your valuable space to /home even though it is a production server?

Here is a quick guide on how to take back that space live, while online (of course make sure you have backups just in case something goes wrong!):

First we will reduce our home dir by 100G:

lvreduce -L -100G /dev/mapper/centos-home
WARNING: Reducing active and open logical volume to <5.12 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce centos/home? [y/n]: y
Size of logical volume centos/home changed from <105.12 GiB (26910 extents) to <5.12 GiB (1310 extents).
Logical volume centos/home successfully resized.

Now let's give it back to /root:


lvextend -l 100%FREE /dev/centos/root
Size of logical volume centos/root changed from 50.00 GiB (12800 extents) to 100.00 GiB (25601 extents).
Logical volume centos/root successfully resized.

OKbut now what does our filesystem magically know what we did with the LV/logical volume? No


[root@disc livefilesystem]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 50G 35G 16G 70% /

devtmpfs 1.9G 0 1.9G 0% /dev
tmpfs 1.9G 0 1.9G 0% /dev/shm
tmpfs 1.9G 8.7M 1.9G 1% /run
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/mapper/centos-home 106G 33M 106G 1% /home
/dev/sda1 1014M 176M 839M 18% /boot
tmpfs 379M 0 379M 0% /run/user/0

Maybe we could just remount it? No



[root@disc livefilesystem]# mount -o remount /
[root@disc livefilesystem]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 50G 35G 16G 70% /

How do we resize the filesystem? xfs_growfs of course!


xfs_growfs /dev/mapper/centos-root
meta-data=/dev/mapper/centos-root isize=512 agcount=4, agsize=3276800 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=13107200, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal bsize=4096 blocks=6400, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 13107200 to 26215424

Now it's all good!


[root@disc livefilesystem]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 100G 35G 66G 35% /
devtmpfs 1.9G 0 1.9G 0% /dev
tmpfs 1.9G 0 1.9G 0% /dev/shm
tmpfs 1.9G 8.7M 1.9G 1% /run
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/mapper/centos-home 106G 33M 106G 1% /home
/dev/sda1 1014M 176M 839M 18% /boot
tmpfs 379M 0 379M 0% /run/user/0


Tags:

centos, reallocate, volume, anotherdo, defaults, allocating, server, online, backups, reduce, dir, lvreduce, dev, mapper, reducing, active, gib, filesystem, etc, extents, successfully, resized, lvextend, ok, magically, lv, disc, livefilesystem, df, avail, mounted, devtmpfs, tmpfs, shm, sys, fs, cgroup, sda, user, remount, mount, resize, xfs_growfs, meta, isize, agcount, agsize, blks, sectsz, attr, projid, crc, finobt, spinodes, bsize, imaxpct, sunit, swidth, naming, ascii, ci, ftype, lazy, realtime, extsz, rtextents,

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