Resize root lvm partition

filesystemslvmpartitionresize2fs

I have a dedicated server with 2 TB storage.

My problem is that the whole storage is allotted to the root partition.

Whenever I try to resize it using lvresize, the root partition gets corrupted and then I have to reprovision the server.

Is there any option to resize the root partition without unmounting in lvm? I am trying to reduce the root partition to 100GB.

Vgs

root@s93079:/home/customer# vgs
  VG        #PV #LV #SN Attr   VSize VFree
  s93079-vg   1   2   0 wz--n- 1.82t    0

Lvs

LV     VG        Attr       LSize  Pool Origin Data%  Meta
%  Move Log Cpy%Sync Convert
  root   s93079-vg -wi-ao----  1.79t

  swap_1 s93079-vg -wi-ao---- 32.00g

Fdisk – l

Device     Boot  Start        End    Sectors  Size Id Type
/dev/sda1  *      2048     499711     497664  243M 83 Linux
/dev/sda2       501758 3907028991 3906527234  1.8T  5 Extend
/dev/sda5       501760 3907028991 3906527232  1.8T 8e Linux

Disk /dev/mapper/s93079--vg-root: 1.8 TiB, 1965782204416 byt
es, 3839418368 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/s93079--vg-swap_1: 32 GiB, 34355544064 byte
s, 67100672 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Vgdisplay

 --- Volume group ---
  VG Name               s93079-vg
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               1.82 TiB
  PE Size               4.00 MiB
  Total PE              476870
  Alloc PE / Size       476870 / 1.82 TiB
  Free  PE / Size       0 / 0
  VG UUID               dPrEwA-77pM-pGai-9jZB-ldMZ-iL20-HAe9
Dj

lvdisplay /dev/s93079-vg/root

 --- Logical volume ---
  LV Path                /dev/s93079-vg/root
  LV Name                root
  VG Name                s93079-vg
  LV UUID                bpGNau-XirV-P7PA-8d6k-OCOy-TAwN-HXl
FVI
  LV Write Access        read/write
  LV Creation host, time s93079, 2016-08-27 09:22:05 -0500
  LV Status              available
  # open                 1
  LV Size                1.79 TiB
  Current LE             468679
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           254:0

Lvdisplay /dev/s93079-vg/swap_1

--- Logical volume ---
 LV Path                /dev/s93079-vg/swap_1
 LV Name                swap_1
 VG Name                s93079-vg
 LV UUID                j74PLZ-E9gK-9Bbb-EkKq-xRJv-TuU4-FgH
gm
 LV Write Access        read/write
 LV Creation host, time s93079, 2016-08-27 09:22:05 -0500
 LV Status              available
 # open                 2
 LV Size                32.00 GiB
 Current LE             8191
 Segments               1
 Allocation             inherit
 Read ahead sectors     auto
 - currently set to     256
 Block device           254:1

Df – h

/dev/dm-0       1.8T  923M  1.7T   1% /
udev             10M     0   10M   0% /dev
tmpfs           3.2G  8.5M  3.2G   1% /run
tmpfs           7.9G     0  7.9G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           7.9G     0  7.9G   0% /sys/fs/cgroup
/dev/sda1       236M   33M  191M  15% /boot

Best Answer

No, not safely. From what I have read, the VG must be available (vgchange --available y, but not mounted). I recommend that you boot from a liveCD or USB so that you have tools loaded into memory, but all of your filesystems not mounted.

Check the file system, we don't want to resize something in an inconsistent state

e2fsck -f /dev/s93079-vg/root

Resize the actual filesystem, a little smaller than the final target.

resize2fs /dev/s93079-vg/root 90G

Now, shrink the LVM to the desired size

lvreduce -L 100G /dev/s93079-vg/root

Finally, grow the the root filesystem to match the target LVM volume

resize2fs /dev/s93079-vg/root

While I browsed several guides, the most helpful blog I found on the topic was https://blog.shadypixel.com/how-to-shrink-an-lvm-volume-safely/

Related Solutions

Debian – How to Move Root (/) to a New Partition

I'd suggest using LVM. To switch over, something like this:

Create a physical volume (pvcreate) on your existing /dev/sda2 (Windows partition)
Create a volume group consisting of just /dev/sda2 (vgcreate)
Create a logical volume to hold your / and /home (any reason you're splitting them? You don't need to.) (lvcreate)
mkfs the two new logical volumes (device: /dev/mapper/vgname-lvname)
If you're not already booted from a rescue disc, boot from one (you could use the Debian install disc, just switch to a terminal at the appropriate point, or alternatively a Ubuntu disc)
mount the new logical volumes (or just one, if you decide not to split). If you mount both, make sure to mount home inside the new root (e.g., as /new-root/ and /new-root/home) Mount your old rootfs somewhere, too.
use tar to copy the files over. Something like ( cd /old-root && tar --one-file-system -c . ) | ( cd /new-root && tar vx )
chroot into your new root filesystem, and:
1. change /etc/fstab to give the proper root filesystem
2. mount /proc and /sys and /boot (inside the chroot)
3. update-initramfs -u
4. update-grub
5. if you're paranoid, look at the generated /boot/grub/grub.cfg to check that it picked up the new rootfs.
6. exit the chroot
Finally, unmount the filesystems you mounted (starting with /new-root/{proc,sys,boot}), and reboot.
Confirm you've booted to the new root filesystem. E.g., check /proc/mounts. Confirm your data is present. (You do have backups too, right?) VERY IMPORTANT.
This is the point of no return. The next steps destroy your old partitions.
You can now pvcreate your old partitions, then add them to your volume group (vgextend)
You can now resize your / and /home logical volumes using lvextend followed by resize2fs (or whichever tool for your filesystem). This can be done online, with your system running.

Once you're on LVM, any future disk changes are much easier. You can use the LVM commands to do pretty much any disk change, with the system running even.

(Note: I haven't done this for a bit, I may have missed a step or two, but I'm pretty sure I haven't missed anything catastrophic. And of course, your original install & data is still around until after you've confirmed you're booted onto the new rootfs)

DD Command – How to Clone a Partition from Disk Image

# losetup --find --show --partscan --read-only 2013-02-09-wheezy-raspbian.img
/dev/loop7
# dd if=/dev/loop7p2 of=/dev/narnia bs=1M

If --partscan doesn't work, you can also use one of:

# partx -a /dev/loop7
# kpartx /dev/loop7

or similar partition mapping solutions.

You should probably mount it first just to see if it's the right thing or what.

Of course you can also read the fdisk output and give dd the skip=131072 or whatever directly, i.e. make it skip that many blocks of input so it starts reading at where the partition is located; but it's nicer to see actual partitions with a loop device.

Best Answer

Related Solutions

Debian – How to Move Root (/) to a New Partition

DD Command – How to Clone a Partition from Disk Image

Related Question