Re: managing the swap space size on fedora

[Angelo Moreschini <mrangelo.fedora@xxxxxxxxx>]

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 ?

 

Thank you

Angelo

On Sat, Jun 13, 2015 at 9:28 PM, Dario Lesca <d.lesca@xxxxxxxxxx> wrote:

Il giorno sab, 13/06/2015 alle 17.01 +0300, Angelo Moreschini ha
scritto:

> Hi,
> I need to adjust the swap space of my computer, and using the
> commands lsblk e swapon -s :
> I got the following output
> - =-=-=-=-=-=-
> [angelo_dev@localhost ~]$ sudo lsblk
> NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
> sda 8:0 0 931.5G 0 disk
> ├─sda1 8:1 0 500M 0 part /boot
> └─sda2 8:2 0 931G 0 part
> ├─fedora_localhost-swap 253:0 0 7.8G 0 lvm [SWAP]
> ├─fedora_localhost-root 253:1 0 50G 0 lvm /
> └─fedora_localhost-home 253:2 0 873.2G 0 lvm /home
> sr0 11:0 1 1024M 0 rom
> [angelo_dev@localhost ~]$ swapon -s
> Filename       Type    Size   Used    Priority
> /dev/dm-0 partition   8126460 0       -1
> - =-=-=-=-=-=-
>
> This makes me think that the swap space on my computer resides on the
> partition / dev / dm-0, which is 'managed by LVM, and' of about 8 GB.
> The RAM of the computer and 'GB, and I would initially try to bring
> the swap space to 16 GB (after I might try other values ....).
>
> Since the swap partition and 'managed by LVM should not be hard to
> change its size, but it is still fairly inexperienced I would get a
> little help to do this.

Your swap partition is /dev/fedora_localhost-swap

take a look at how much free space you have in LVM

> sudo pvscan
>   PV /dev/mapper/luks-04cb7d3f-fb60-42ca-9dbe-1ae18433f62d   VG vg_dododell   lvm2 [196,28 GiB / 7,72 GiB free]
>   Total: 1 [196,28 GiB] / in use: 1 [196,28 GiB] / in no VG: 0 [0   ]

In my case 7,72 GiB free.
If you have sufficient free space in LVM you can extend swap partition
with:

> sudo pvresize --size +6G /dev/fedora_localhost-swap

If you do not have sufficient LVM space free, you can shrink some other
partition, like /home, you can do that in single user mode, or logging
in with root from CTRL+Alt+F2 and without other active users, umount
/home, restrict filesystem (example 11Gb) , restrict partition (example
10 Gb), extend filesystem to max partition.

At this point you can extend the swap LVM partition.

When you have extend the swap partition, you must extend the swap area
with this command:

> swapoff /dev/fedora_localhost-swap
> mkswap /dev/fedora_localhost-swap
> swapon /dev/fedora_localhost-swap

Hope this help

Ciao

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