Il giorno dom, 14/06/2015 alle 12.29 +0300, Angelo Moreschini ha scritto:
Ciao Dario,

I need a little explanation, because  I am not able to well understood  about how to get of the value of the free space.

I made some tests:

using the command pvscan I get this output:
-----
PV /dev/sda2   VG fedora_localhost   lvm2 [931.02 GiB / 64.00 MiB free]
Total: 1 [931.02 GiB] / in use: 1 [931.02 GiB] / in no VG: 0 [0   ]
-----
what means this ?
I can think this output concern ALL the Volume Group of LVM:
And the row up seem to indicate that they are (only) 64 MB free
(but what means "/ in no VG: 0 [0   ]"  in the row down?)


I made the same test (inside the lvm environment) using the command lvscan:
this time I got this output:
-----
lvm> lvscan
  ACTIVE            '/dev/fedora_localhost/swap' [7.75 GiB] inherit
  ACTIVE            '/dev/fedora_localhost/home' [873.21 GiB] inherit
  ACTIVE            '/dev/fedora_localhost/root' [50.00 GiB] inherit
----- OK!    the total is 930.96  ------

that the second control confirm the former one, and it shows also more details...

But what does not enter in my head, is the fact that the (huge) quantity of free space (845449680 ) of the  "home" partition is not reported when I used the command pvscan : ...

This is the output of the command line df -k:
-----
[angelo_dev@localhost ~]$ df -k
Filesystem                                      1K-blocks     Used         Available Use% Mounted on
/dev/mapper/fedora_localhost-root      51475068     10518776  38318468  22% /
devtmpfs                                          4046300        0             4046300   0% /dev
tmpfs                                               4057324      152           4057172   1% /dev/shm
tmpfs                                               4057324      904           4056420   1% /run
tmpfs                                              4057324        0             4057324   0% /sys/fs/cgroup
tmpfs                                              4057324      668           4056656   1% /tmp
/dev/mapper/fedora_localhost-home   901125392   9878132    845449680   2% /home
/dev/sda1                                        487652        105670      352286    24% /boot
tmpfs                                             811468         28             811440   1% /run/user/1001
-----

in short: I would like understand because I have to ask (shrink) free space, in order to expand the swap partition - in the moment that - the home partition (THAT BELONGS TO THE SAME VG) already has  a huge amount of free space ?

The free space is into filesystem, and not into LVM.
The free space into filesystem is not useful vie LVM,
You must be transferred a little bit of free space from filesystem to LVM
Shrink filesystem then shrink LVM partition.

When you install Fedora, and do not do a manual partition, anaconda use all disk space for all default partition, swap(8Gb), /(50 Gb) and /home (all the rest), 900Gb in your case.

Then now, you have a huge /home, filling for 9Gb (2%), and 0 Gb of LVM free for extend other FS or Swap.

When I install, I do not allocate all space but only a little bit (or what I have need) for my filesystem. Because, after, is more simple extend rater than shrink.

Now I suggest you to shrink /home to 200 Gb (or what do you want) and leave more free space to assign where it's necessary or create new volume.

To do that follow the my previous generic procedure.
If you have ext4 FS (blkid is your friend), after you have unmount /home, the command are:

sudo umount /dev/fedora_localhost/home # umount fs
sudo fsck.ext4 -f /dev/fedora_localhost/home # check fs
sudo resize2fs /dev/fedora_localhost/home 190G # shrink fs to a little bit less what you want
sudo lvresize --size 200G /dev/fedora_localhost/home # Resize partition to what you want
sudo resize2fs /dev/fedora_localhost/home # extend the FS to partition size, what you want.
sudo mount -a
sudo pvscan

At this point you'll have a lot of free space to do whatever you want.

IMPORTANT:
Before of all, do a full backup of your important data, if I or you have written something wrong , you will need to reinstall from scratch

Ciao.

-- 
Dario Lesca
(inviato dal mio Linux Fedora 22 con Gnome 3.16)