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the question is :

How can I create a new 3GB logical volume or partition on the system below?

I tried many many times but without being successful...

There is no live cd provided as this is for an exam.

I tried many times and got the same error while trying to create a 3GB partition on /dev/sda2.

There are the logs and the screenshots showing the error message during the reboot.

[root@resize2 ~]# lsblk


NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 30G 0 disk
├─sda1 8:1 0 500M 0 part /boot
└─sda2 8:2 0 29.5G 0 part
├─vggroup-swap 253:0 0 2G 0 lvm [SWAP]
├─vggroup-root 253:1 0 22.7G 0 lvm /
└─vggroup-home 253:2 0 4.9G 0 lvm /home
sr0 11:0 1 6.6G 0 rom /run/media/marc/CentOS 7 x86_64
[root@resize2 ~]#
[root@resize2 ~]# df -Th


Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/vggroup-root ext4 23G 3.3G 18G 16% /
devtmpfs devtmpfs 912M 0 912M 0% /dev
tmpfs tmpfs 921M 84K 921M 1% /dev/shm
tmpfs tmpfs 921M 8.7M 912M 1% /run
tmpfs tmpfs 921M 0 921M 0% /sys/fs/cgroup
/dev/sda1 ext4 477M 95M 353M 22% /boot
/dev/mapper/vggroup-home ext4 4.7G 51M 4.4G 2% /home
/dev/sr0 iso9660 6.6G 6.6G 0 100% /run/media/marc/CentOS 7 x86_64
[root@resize2 ~]#
[root@resize2 ~]# pvdisplay


--- Physical volume ---
PV Name /dev/sda2
VG Name vggroup
PV Size 29.50 GiB / not usable 3.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 7550
Free PE 0
Allocated PE 7550
PV UUID fbhnuB-wTks-mkMy-9nfX-7ISJ-3MOi-E3IPhV

[root@resize2 ~]#
[root@resize2 ~]# vgdisplay


--- Volume group ---
VG Name vggroup
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 1
Act PV 1
VG Size 29.49 GiB
PE Size 4.00 MiB
Total PE 7550
Alloc PE / Size 7550 / 29.49 GiB
Free PE / Size 0 / 0
VG UUID ajso7W-2IyX-fE0A-16Jf-buut-O6x4-S4ySY3

[root@resize2 ~]#
[root@resize2 ~]# lvdisplay


--- Logical volume ---
LV Path /dev/vggroup/root
LV Name root
VG Name vggroup
LV UUID eUA7Mk-zekT-LNx4-0GTX-LaKk-0TxC-fCbZ0S
LV Write Access read/write
LV Creation host, time localhost, 2017-12-28 12:33:13 +0000
LV Status available
# open 1
LV Size 22.66 GiB
Current LE 5800
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1

--- Logical volume ---
LV Path /dev/vggroup/swap
LV Name swap
VG Name vggroup
LV UUID xoQkXQ-csCo-0MWt-poDC-pwQk-NcWe-fZDwVH
LV Write Access read/write
LV Creation host, time localhost, 2017-12-28 12:33:16 +0000
LV Status available
# open 2
LV Size 1.95 GiB
Current LE 500
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0

--- Logical volume ---
LV Path /dev/vggroup/home
LV Name home
VG Name vggroup
LV UUID 7UAzWG-i8CH-ywMV-4MMq-tsiJ-rUeI-Conb3u
LV Write Access read/write
LV Creation host, time localhost, 2017-12-28 12:33:17 +0000
LV Status available
# open 1
LV Size 4.88 GiB
Current LE 1250
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2

[root@resize2 ~]#
[root@resize2 ~]#
[root@resize2 ~]# parted /dev/sda print free


Model: ATA QEMU HARDDISK (scsi)
Disk /dev/sda: 32.2GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number Start End Size Type File system Flags
32.3kB 1049kB 1016kB Free Space
1 1049kB 525MB 524MB primary ext4 boot
2 525MB 32.2GB 31.7GB primary lvm
32.2GB 32.2GB 16.8MB Free Space

[root@resize2 ~]#
[root@resize2 ~]#
[root@resize2 ~]# fdisk -l

Disk /dev/sda: 32.2 GB, 32212254720 bytes, 62914560 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 label type: dos
Disk identifier: 0x0009cecd

Device Boot Start End Blocks Id System
/dev/sda1 * 2048 1026047 512000 83 Linux
/dev/sda2 1026048 62881791 30927872 8e Linux LVM

Disk /dev/mapper/vggroup-swap: 2097 MB, 2097152000 bytes, 4096000 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/vggroup-root: 24.3 GB, 24326963200 bytes, 47513600 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/vggroup-home: 5242 MB, 5242880000 bytes, 10240000 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

[root@resize2 ~]#
[root@resize2 ~]# fdisk /dev/sda2
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0xc924a0b7.

Command (m for help): p

Disk /dev/sda2: 31.7 GB, 31670140928 bytes, 61855744 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 label type: dos
Disk identifier: 0xc924a0b7

Device Boot Start End Blocks Id System

Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p):
Using default response p
Partition number (1-4, default 1):
First sector (2048-61855743, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-61855743, default 61855743): +3G
Partition 1 of type Linux and of size 3 GiB is set

Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 22: Invalid argument.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
[root@resize2 ~]#
[root@resize2 ~]# partprobe
Warning: Unable to open /dev/sr0 read-write (Read-only file system). /dev/sr0 has been opened read-only.
Warning: Unable to open /dev/sr0 read-write (Read-only file system). /dev/sr0 has been opened read-only.
Warning: Unable to open /dev/sr0 read-write (Read-only file system). /dev/sr0 has been opened read-only.
[root@resize2 ~]#
[root@resize2 ~]#
[root@resize2 ~]# systemctl reboot

enter image description here

enter image description here

Does anyone know why I got this error and how to fix it in order to create a 3GB partition or 3GB logical volume on that system?

Thank you for your help

Update #1

I tried previously with fdisk /dev/sda but got an error message “Value out of range” while trying to create the 3 GB partition.

[root@resize2 ~]# lsblk
NAME             MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda                8:0    0   30G  0 disk
├─sda1             8:1    0  500M  0 part /boot
└─sda2             8:2    0 29.5G  0 part
  ├─vggroup-swap 253:0    0    2G  0 lvm  [SWAP]
  ├─vggroup-root 253:1    0 22.7G  0 lvm  /
  └─vggroup-home 253:2    0  4.9G  0 lvm  /home
sr0               11:0    1  6.6G  0 rom  /run/media/marc/CentOS 7 x86_64
[root@resize2 ~]# fdisk /dev/sda
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): p

Disk /dev/sda: 32.2 GB, 32212254720 bytes, 62914560 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 label type: dos
Disk identifier: 0x0009cecd

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1026047      512000   83  Linux
/dev/sda2         1026048    62881791    30927872   8e  Linux LVM

Command (m for help): n
Partition type:
   p   primary (2 primary, 0 extended, 2 free)
   e   extended
Select (default p):
Using default response p
Partition number (3,4, default 3):
First sector (62881792-62914559, default 62881792):
Using default value 62881792
Last sector, +sectors or +size{K,M,G} (62881792-62914559, default 62914559): +3G
Value out of range.
Last sector, +sectors or +size{K,M,G} (62881792-62914559, default 62914559):

I don't actually need a 3 GB partition but a 3GB logical volume.

How can I then create this 3 GB logical volume in the volume group due to the lack of free space?

2 Answers 2

0

First of all the following line is wrong:

fdisk /dev/sda2 

/dev/sda2 is a partition, not a whole disk. You should pass /dev/sda as input to fdisk, then manipulate primary partition 2 inside fdisk.

Just note that you sda2 is 29.5G and it contains logical partitions that sum of to 2+22.7+4.9 =~ 29.5G so sda2 seems full. To add 3GB partition you will either need to use unallocated space on HD, or to resize sda2 (which you cannot do with fdisk)

0
0

You need lvcreate for creating an new LV, not fdisk. But, of course, you need free space in the VG which you currently do not have.

The boot problem could result from the initrd not containing the modules necessary for LVM.

7
  • How can I then make some room in the VG without adding any disks?Thanks Jan 14, 2018 at 20:43
  • @qwerty1805 You can reduce the size of an existing (unmounted) LV. See man lvreduce, especially --resizefs. Jan 14, 2018 at 20:56
  • As I can't reduce the vggroup-root, the only solution I have would be to reduce the vggroup-swap and the vggroup-home? Is that correct? Jan 15, 2018 at 17:30
  • @qwerty1805 I don't know why you think you cannot reduce the root partition. I would suggest to copy the contents of /home into the root volume and delete the home LV. Jan 16, 2018 at 8:35
  • Thank you for the answer. As the root partition is mounted and, as far as I understood, a partition needs to be unmounted before being reduced. Ann without live cd ,I presume I can’t reduce the root partition as it is currently used by the system. Am I wrong? Jan 17, 2018 at 8:27

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