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How to Rezize Partition on LVM

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  How to Rezize Partition on LVM ray <ray@aarden.us> - 2015-10-24 03:30 +0200
    Re: How to Rezize Partition on LVM Charlie Kravetz <cjk@teamcharliesangels.com> - 2015-10-24 04:40 +0200
    Re: How to Rezize Partition on LVM Mario Castelán Castro <marioxcc.MT@yandex.com> - 2015-10-24 04:40 +0200
    Re: How to Rezize Partition on LVM Pascal Hambourg <pascal@plouf.fr.eu.org> - 2015-10-24 17:50 +0200
      Re: How to Rezize Partition on LVM ray <ray@aarden.us> - 2015-10-25 14:00 +0100
        Re: How to Rezize Partition on LVM Pascal Hambourg <pascal@plouf.fr.eu.org> - 2015-10-25 16:00 +0100
          Re: How to Rezize Partition on LVM ray <ray@aarden.us> - 2015-10-25 20:10 +0100
          Re: How to Rezize Partition on LVM ray <ray@aarden.us> - 2015-10-25 20:30 +0100
            Re: How to Rezize Partition on LVM Mario Castelán Castro <marioxcc.MT@yandex.com> - 2015-10-25 20:50 +0100
              Re: How to Resize Partition on LVM ray <ray@aarden.us> - 2015-10-26 02:50 +0100
                Re: How to Resize Partition on LVM Mario Castelán Castro  <marioxcc.MT@yandex.com> - 2015-10-26 03:20 +0100
                Re: How to Resize Partition on LVM Pascal Hambourg <pascal@plouf.fr.eu.org> - 2015-10-26 10:00 +0100
                  Re: How to Resize Partition on LVM Mario Castelán Castro  <marioxcc.MT@yandex.com> - 2015-10-26 15:20 +0100
                    Re: How to Resize Partition on LVM ray <ray@aarden.us> - 2015-10-27 05:10 +0100

#159710 — How to Rezize Partition on LVM

I would like to resize the /home partition but it is mounted, and when umount is run, it errors with 'busy'.  

System Configuration:
I installed jessie on a laptop with one SSD.  I used guided partitioning and selected the whole drive with multiple partitions.  The /home now takes up 420 GB.  I would like to reduce that to 20 GB to make room for another partition.  

What are the methods reduce this partition?

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#159712

On Fri, 23 Oct 2015 18:05:55 -0700 (PDT)
ray <ray@aarden.us> wrote:

>I would like to resize the /home partition but it is mounted, and when umount is run, it errors with 'busy'.  
>
>System Configuration:
>I installed jessie on a laptop with one SSD.  I used guided partitioning and selected the whole drive with multiple partitions.  The /home now takes up 420 GB.  I would like to reduce that to 20 GB to make room for another partition.  
>
>What are the methods reduce this partition?
>

I have always booted from a live cd or usb to do the resizing. That
keeps the partition from being mounted.

-- 
Charlie Kravetz
Linux Registered User Number 425914
[http://linuxcounter.net/user/425914.html]
Never let anyone steal your DREAM.   [http://keepingdreams.com]

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#159714

El 23/10/15 a las 20:05, ray escribió:
> I would like to resize the /home partition but it is mounted, and when umount is run, it errors with 'busy'.
>
> System Configuration:
> I installed jessie on a laptop with one SSD.  I used guided partitioning and selected the whole drive with multiple partitions.  The /home now takes up 420 GB.  I would like to reduce that to 20 GB to make room for another partition.
>
> What are the methods reduce this partition?

In order to resize a partition that is on LVM, you must *first* reduce 
the size of the filesystem, *then* reduce the size of the logical 
volume, to exactly the same size (or the LVM LV bigger than the 
filesystem, but that is wasteful and does not make sense). To make sure 
that the LVM LV and filesystem are the same size, specify the size to 
all tools in bytes to be sure. Instead of using a bigger unit like MB or 
MiB. Make the conversion and make it a multiple of 1 MiB, for example, 
if you want 400 GB, rounding to the nearest multiple of 1 MiB gives 
400000286720 bytes.

To shrink a filesystem, you will need to use a filesystem-specifc tool. 
For ext{2,3,4} you can use "resize2fs"; the filesystem needs to be 
unmounted in order to make it smaller, but you can make a filesystem 
bigger either mounted or unmounted mounted (but this is the opposite you 
need in this case).

To resize a logical volume, take a look into the documentation (man 
page) of the tool "lvresize".

The only requirement that will cause a minor inconvenience is to have 
your partition unmounted. Since you want to resize /home, it will 
normally be used by many programs, including your desktop environment; 
and therefore there is no trivially easy way to unmount it while using 
your graphical environment.

You should be able to boot in single user mode and do the resizing with 
/home unmounted. I have not done that in Debian 8 yet (which a different 
boot system by default than Debian 7).

You can also boot from a Live CD image of Debian and perform the 
resizing from there; however, there is no need to burn the image to an 
actual CD, and it is a waste of resources (money and natural resources) 
unless it is actually required for a different and good reason. Instead, 
put the CD image as a file into your root partition and boot from there 
using GRUB. There is plenty of information about how to boot an ISO 
image from GRUB in its manual and scattered in the web. For example, 
with a very quick search I found this: 
<http://xmodulo.com/boot-iso-image-from-grub.html>; do your own research.

A web search will bring more information about resizing in general. 
Resizing is a common task when installing operating systems. *I heavily 
recommend against using Google.* Google has way too much power and don't 
uses it for good (neither it should have that much power in the first 
place). For example, DuckDuckGo comes pre-configured in Iceweasel; it 
promises to not to track, and it isn't an Internet tyrant (unlike 
Google), so consider using it instead.

Standard recommendation of making a backup applies.

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#159733

ray a écrit :
> I would like to resize the /home partition but it is mounted, and when
> umount is run, it errors with 'busy'.  
> 
> I used guided partitioning and selected the whole drive with multiple
> partitions.  The /home now takes up 420 GB.  I would like to reduce that
> to 20 GB to make room for another partition.  

Are you talking about plain partitions or LVM logical volumes ? In the
subject you mentionned LVM, but in the body you mention only partitions.
Regarding your question, this is not the same at all.

It is too late now, but here is my advice for future installations using
LVM : if you don't plan to use btrfs, don't allocate all the space to
the logical volumes, leave some free space for future allocation.
Growing an ext2/3/4 filesystem is easy and can be done online (without
unmounting it). However online shrinking is only supported with a btrfs
filesystem. Some filesystems such as XFS don't even allow offline shrinking.

/home can be unmounted only when no process uses it. In practice it
means that you cannot be logged in as a regular user (with its home
directory in /home) but directly as root, without using 'su' or 'sudo'.
In my experience it is not necessary to boot in single user mode or from
another system. Just log in as root in a tty console.

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#159761

I would like to than everyone for the input.  Here is how it was completed:

Boot into GUI mycomp as root

# df -h
Filesystem                    Size  Used Avail Use% Mounted on
/dev/dm-0                     8.2G  2.9G  4.9G  38% /
udev                           10M     0   10M   0% /dev
tmpfs                         3.2G  9.2M  3.2G   1% /run
tmpfs                         7.9G   68K  7.9G   1% /dev/shm
tmpfs                         5.0M  4.0K  5.0M   1% /run/lock
tmpfs                         7.9G     0  7.9G   0% /sys/fs/cgroup
/dev/sda1                     236M   46M  178M  21% /boot
/dev/mapper/mycomp--vg-var   2.7G  351M  2.2G  14% /var
/dev/mapper/mycomp--vg-tmp   360M  2.1M  335M   1% /tmp
/dev/mapper/mycomp--vg-home  427G  136M  405G   1% /home
tmpfs                         1.6G  4.0K  1.6G   1% /run/user/118
tmpfs                         1.6G  8.0K  1.6G   1% /run/user/0
root@mycomp:~# resize2fs /dev/mapper/mycomp--vg-home 5G
Filesystem at /dev/mapper/mycomp--vg-home is mounted on /home; on-line resizing required
resize2fs: On-line shrinking not supported

Rebooting into command line interface for root worked, the /home partition was not mounted.

---------------------------------------------------------------------------

# lvreduce -L 5G /dev/mapper/mycomp--vg-home
  WARNING: Reducing active and open logical volume to 5.00 GiB
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce home? [y/n]: y
  Size of logical volume mycomp-vg/home changed from 433.32 GiB (110931 extents) to 5.00 GiB (1280 extents).
  Logical volume home successfully resized

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#159764

ray a écrit :
> I would like to than everyone for the input.  Here is how it was completed:
> 
> Boot into GUI mycomp as root

I thought that logging as root was prohibited by GUI display managers.

> # df -h
> Filesystem                    Size  Used Avail Use% Mounted on
(...)
> /dev/mapper/mycomp--vg-home  427G  136M  405G   1% /home
(...)
> root@mycomp:~# resize2fs /dev/mapper/mycomp--vg-home 5G
> Filesystem at /dev/mapper/mycomp--vg-home is mounted on /home; on-line resizing required
> resize2fs: On-line shrinking not supported

You need to unmount /home first. If you're logged as root, it should work.

> Rebooting into command line interface for root worked, the /home partition was not mounted.

What do you call "command line interface for root" ? Single user mode ?

> # lvreduce -L 5G /dev/mapper/mycomp--vg-home
>   WARNING: Reducing active and open logical volume to 5.00 GiB
>   THIS MAY DESTROY YOUR DATA (filesystem etc.)
> Do you really want to reduce home? [y/n]: y
>   Size of logical volume mycomp-vg/home changed from 433.32 GiB (110931 extents) to 5.00 GiB (1280 extents).
>   Logical volume home successfully resized

I hope you reran the resize2fs command successfully before doing this.
Otherwise you just ruined your /home filesystem.

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#159776

On Sunday, October 25, 2015 at 10:00:08 AM UTC-5, Pascal Hambourg wrote:
> (...)
> I thought that logging as root was prohibited by GUI display managers.
That is what I have read.  But I tried it anyway and found it to work.

> (...)
> I hope you reran the resize2fs command successfully before doing this.
> Otherwise you just ruined your /home filesystem.
I did not make a record of that so I am not sure whether I reran resize2fs.   This system has been reboot a few times since then and many configurations altered.  I haven't noticed a failure.

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#159778

Now that the /home logical volume has been reduced, I would like to add a partition in the remaining space or reduce the LV's size to fee the unused space and create a new logical volume. Since the existing LV totally occupies the SSD, I don't see how to do this.

I would appreciate any suggestions on how to complete this.

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#159779

El 25/10/15 a las 13:03, ray escribió:
> Now that the /home logical volume has been reduced, I would like to add a partition in the remaining space or reduce the LV's size to fee the unused space and create a new logical volume. Since the existing LV totally occupies the SSD, I don't see how to do this.
>
> I would appreciate any suggestions on how to complete this.

It seems like confusing LV with PV. An *LVM group* presents itself to 
the block devices that contains it as a *physical volume* (PV), in turn, 
LVM provides *logical volumes* (LV) over which you may place 
filesystems. Don't confuse those 3 concepts. If you want to make a 
partition outside LVM, you would have to reduce the LVM physical volume, 
not the LVM logical volume (which you already did).

If you already reduced the filesystem and the logical volume, then there 
is free space within your LVM volume group; there may be no "free space 
in the SSD" (space not assigned to any partition or the MBR), but that 
is how it is supposed to be. The reason to use LVM is to put filesystems 
in logical volumes within your volume group to get the benefits of 
logical volume management, not as partitions outside your volume group, 
because you lose those benefits.

You can create logical volumes with "lvcreate". Read the manual!

   man lvm

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#159784 — Re: How to Resize Partition on LVM

Mario,

Thank you for the review.

Yes, there is free space in the LVM.  I have gone through the manual many times (today and the last several months) and don't see a method to add a pv or vg.  It seems to add a pv, it needs a device.  And to add a vg, it needs a pv.  How can I add either?

Displaying the resize pv:
# pvdisplay -v -m
    DEGRADED MODE. Incomplete RAID LVs will be processed.
    Scanning for physical volume names
  --- Physical volume ---
  PV Name               /dev/sda5
  VG Name               mycomp-vg
  PV Size               55.00 GiB / not usable 3.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              14079
  Free PE               1695
  Allocated PE          12384
                 (the file system is smaller than the pv)  
 lsblk
NAME                   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda                      8:0    0   477G  0 disk 
├─sda1                   8:1    0   243M  0 part /boot
├─sda2                   8:2    0     1K  0 part 
└─sda5                   8:5    0 476.7G  0 part 
  ├─mycomp--vg-root   254:0    0   8.4G  0 lvm  /
  ├─mycomp--vg-var    254:1    0   2.8G  0 lvm  /var
  ├─mycomp--vg-swap_1 254:2    0  31.9G  0 lvm  [SWAP]
  ├─mycomp--vg-tmp    254:3    0   380M  0 lvm  /tmp
  └─mycomp--vg-home   254:4    0     5G  0 lvm  /home
     

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#159785 — Re: How to Resize Partition on LVM

According to "man lvm", to add a physical volume to a volume group, the 
right command is "vgextend" (the name is because you make a volume group 
(VG) larger by adding more storage space for it, in a new physical 
volume). To create a new volume group, the command is "vgcreate". But if 
you want to add a filesystem, you *need not* (and very likely, should 
not) add a volume group nor a physical volume. What you need is: (1) 
Create a local volume within your existing volume groups; use lvcreate 
for that. (2) Make a filesystem with "mkfs.ext4" (or similar, for other 
filesystem type). (3) Optionally add a corresponding entry in /etc/fstab 
and mount the new filesystem.

A typical structure is this (where "->" means "stored in"); it is not 
the only possible layout, but it is likely the most common one and seems 
to be the one you are using:

Files -> Filesystem -> LVM LV -> LVM VG -> LVM PV
   -> Partition -> Disc or SSD

The structure is NOT hierarchical, and not all of these arrows represent 
the same relationship between components. In particular, note that a LVM 
VG does both grouping and ungrouping: It *takes* storage space from 
(possibly several) physical volumes, and it *provides* storages space to 
(possibly several) *logical volumes*.

The main information resource are the main pages. Also see 
<http://www.tldp.org/HOWTO/LVM-HOWTO/index.html>. Do your own research.

El 25/10/15 a las 19:22, ray escribió:
> Mario,
>
> Thank you for the review.
>
> Yes, there is free space in the LVM.  I have gone through the manual many times (today and the last several months) and don't see a method to add a pv or vg.  It seems to add a pv, it needs a device.  And to add a vg, it needs a pv.  How can I add either?
>
> Displaying the resize pv:
> # pvdisplay -v -m
>      DEGRADED MODE. Incomplete RAID LVs will be processed.
>      Scanning for physical volume names
>    --- Physical volume ---
>    PV Name               /dev/sda5
>    VG Name               mycomp-vg
>    PV Size               55.00 GiB / not usable 3.00 MiB
>    Allocatable           yes
>    PE Size               4.00 MiB
>    Total PE              14079
>    Free PE               1695
>    Allocated PE          12384
>                   (the file system is smaller than the pv)
>   lsblk
> NAME                   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
> sda                      8:0    0   477G  0 disk
> ├─sda1                   8:1    0   243M  0 part /boot
> ├─sda2                   8:2    0     1K  0 part
> └─sda5                   8:5    0 476.7G  0 part
>    ├─mycomp--vg-root   254:0    0   8.4G  0 lvm  /
>    ├─mycomp--vg-var    254:1    0   2.8G  0 lvm  /var
>    ├─mycomp--vg-swap_1 254:2    0  31.9G  0 lvm  [SWAP]
>    ├─mycomp--vg-tmp    254:3    0   380M  0 lvm  /tmp
>    └─mycomp--vg-home   254:4    0     5G  0 lvm  /home
>
>

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#159793 — Re: How to Resize Partition on LVM

ray wrote :
> 
> Displaying the resize pv:
> # pvdisplay -v -m
>     DEGRADED MODE. Incomplete RAID LVs will be processed.

Hmm. Not sure wha that means. Was there anothed disk in the VG ?

>     Scanning for physical volume names
>   --- Physical volume ---
>   PV Name               /dev/sda5
>   VG Name               mycomp-vg
>   PV Size               55.00 GiB / not usable 3.00 MiB
>   Allocatable           yes 
>   PE Size               4.00 MiB
>   Total PE              14079
>   Free PE               1695
>   Allocated PE          12384
>                  (the file system is smaller than the pv)  
>  lsblk
> NAME                   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
> sda                      8:0    0   477G  0 disk 
> ├─sda1                   8:1    0   243M  0 part /boot
> ├─sda2                   8:2    0     1K  0 part 
> └─sda5                   8:5    0 476.7G  0 part 
>   ├─mycomp--vg-root   254:0    0   8.4G  0 lvm  /
>   ├─mycomp--vg-var    254:1    0   2.8G  0 lvm  /var
>   ├─mycomp--vg-swap_1 254:2    0  31.9G  0 lvm  [SWAP]
>   ├─mycomp--vg-tmp    254:3    0   380M  0 lvm  /tmp
>   └─mycomp--vg-home   254:4    0     5G  0 lvm  /home

The sizes don't match. The size of /dev/sda5 is 476 GiB but the PV
within claims its size is only 55 GiB and is almost full. Did you reduce
the PV size in /dev/sda5 with pvresize ?

Now you need to explain what you want to do exactly, because you have
been unclear so far.

Do you want to reduce the partition /dev/sda5 and create a new plain
partition for whatever use (filesystem, new PV for existing or new VG) ?

Then you must reduce /dev/sda5 with whatever partitioning tool, to a
size of at least the PV size, 55 GiB (*not* 55 GB which is only 51.2
GiB, beware if using parted). In the free space on the disk you can
create a new partition.

Or do you want to create a new LV in the existing VG ?

Then, if the new LV size is less than the remaining free space in the VG
(about 6.5 GiB), just use lvcreate to create the LV. If its size must be
bigger than the available free space, then you need to resize the PV
first, up to the size of /dev/sda5.

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#159804 — Re: How to Resize Partition on LVM

> Then you must reduce /dev/sda5 with whatever partitioning tool, to a
> size of at least the PV size, 55 GiB (*not* 55 GB which is only 51.2
> GiB, beware if using parted). In the free space on the disk you can
> create a new partition.

That is why I recommended using complete sizes in bytes.

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#159833 — Re: How to Resize Partition on LVM

I would like to thank everyone to helping.

Looks like it is working.  Here is the action:

With Live GParted, reduce sda5 to minimum ~ 60GB.
Create new partition, sda6 ~420GB.
Booted back to Debian.
pvcreate /dev/sda6
vgcreate xenvg /dev/sda6
lvcreate -l +100%FREE xenvg -n xenlv
mkfs.ext4 -m 0 /dev/xenvg/xenlv

Updated /etc/fstab  last line:
/dev/mapper/xenvg-xenlv /xenfs             ext4        defaults        0     

# mount -a

# ls -a /xenfs
.  ..  lost+found


# df -h
Filesystem                    Size  Used Avail Use% Mounted on
<snip>
/dev/sda1                     236M   49M  176M  22% /boot
/dev/mapper/mycomp--vg-tmp   360M  2.1M  335M   1% /tmp
/dev/mapper/mycomp--vg-var   2.7G  366M  2.2G  15% /var
/dev/mapper/mycomp--vg-home  4.8G  143M  4.4G   4% /home
<snip>
/dev/mapper/xenvg-xenlv       413G   71M  412G   1% /xenfs

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