[PLUG] lvm: reclaim and reallocate space

Dale Snell ddsnell at frontier.com
Wed Aug 3 22:52:39 UTC 2016


On Wed, 3 Aug 2016 12:16:04 -0700, in message
CAArW4Zj-j2pEK-6qJOgyuWd193pwUc4wJxG=+3Xn=h6WJvGUpg at mail.gmail.com,
mitch portland wrote:

> Hi Guys,
> 
> I have a Fedora 21 machine on which I configured the 250Gb drive in
> the following way:
> 
> hobgoblin:~:{619}lsblk
> NAME            MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
> sda               8:0    0 232.9G  0 disk
> ├─sda1            8:1    0   500M  0 part /boot
> └─sda2            8:2    0 232.4G  0 part
>   ├─fedora-swap 253:0    0  15.7G  0 lvm  [SWAP]
>   ├─fedora-root 253:1    0    50G  0 lvm  /
>   └─fedora-home 253:2    0 166.7G  0 lvm  /home
> sr0              11:0    1  1024M  0 rom
> sr1              11:1    1  1024M  0 rom
> hobgoblin:~:{620}df
> Filesystem               Size  Used Avail Use% Mounted on
> devtmpfs                  16G     0   16G   0% /dev
> tmpfs                     16G  122M   16G   1% /dev/shm
> tmpfs                     16G  1.5M   16G   1% /run
> tmpfs                     16G     0   16G   0% /sys/fs/cgroup
> /dev/mapper/fedora-root   50G   38G  9.5G  80% /
> tmpfs                     16G  460K   16G   1% /tmp
> /dev/sda1                477M  177M  271M  40% /boot
> /dev/mapper/fedora-home  164G   11G  146G   7% /home
> tmpfs                    3.2G   28K  3.2G   1% /run/user/2155
> 
> I've been using the machine for over a year, and all's well, except
> that I'm now continually running out of space on the / volume. The
> applications I use install in /opt, and I have to keep many different
> versions around for my work, so space is getting very tight. /home
> has plenty of space though, so I'd like to reallocate most of it to /.
> 
> I've used the OSX disk utility to "pack" a partition's contents into
> it more efficiently, and then reduce the size of the partition so I
> can reallocate it to another. Using that gui tool, the process is all
> very clear and works great.
> 
> When I set up the Fedora 21 machine, there was a very nice gui
> interface for setting up the partitions and logical volumes. But
> Fedora 21 doesn't seem to have an equivalent tool that can be run
> after installation, now that system-config-lvm is no longer
> supported. Command-line lvm looks simple-ish to use; but what I'm not
> clear on is whether it can pack a volume's contents in order to
> create a clear area of unused space before resizing the volume.
> 
> I can't afford to break this machine, so I'm trying to make sure I
> know exactly what I'm doing before I get started.
> 
> Thanks, mitch


Hi Mitch

First off, you should read the man pages for fsadm(8) and
lvresize(8).  You need to resize /home before you can re-size the
logical partition.  The LVM command-line programs are not
particularly difficult to use, but you must be absolutely certain
that you're doing the right thing.  Since my memory is as leaky as
a sieve, I always have to re-read the man pages for any of the
commands I need to use.  :-)

That said, it should not be difficult to re-size /home -- that's
your main worry.  It wouldn't hurt to re-size / either, but
I don't think it's really necessary.

Once that's done, you should be able to use lvresize(8) to shrink
/home, then expand /.

There should be no need to fiddle with the pv* or vg* LVM
commands.  But do read up on the lg* commands.  There are a lot of
them, I know, but they're well worth reading about.

Hope this helps,

--Dale

-- 
“I’ve always felt that a leader should have a strong chin.
Santiago has _no_ chin, and his running mate has several.  This,
to me, is not a good combination.”
    -- Susan Ivanova, “Midnight on the Firing Line”, Babylon 5



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