I recently commissioned a RHEL server and I was made aware of a partition requirement after I was done. I need to create a partition for the software that the client will install.

I have 80GB free from /var and I was wondering if I could reduce its size and create a new partition from the space that I would recover.

Thanks!

You might need to move the /var to new partition instead of creating a new one. Follow the steps mentions in the link below for the same -
https://outhereinthefield.wordpress....her-partition/

If the OP can do that, it would be easier to just create that partition for the application.

If the server uses LVM, and /var is on an ext filesystem, you can do that by booting into single user mode, shrinking the /var filesystem with resize2fs, then shrinking the logical volume with lvreduce. In that order. I.e., don't shrink the logical volume before shrinking the filesystem.

Be careful not to shrink /var too much though. How much space you need depends on the amount of log data your system is likely to generate, and the configuration of logrotate.

Before you do this, check if there is room in any volume group. The easiest command for that is vgs.

If this is too much for you, first give us a map of your disks and partitions. E.g. the output of commands lsblk, vgs, lvs and fdisk -l.

Additional info.

[root@BDOULXXXX var]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 19G 1.1G 18G 6% /
devtmpfs 7.8G 0 7.8G 0% /dev
tmpfs 7.8G 0 7.8G 0% /dev/shm
tmpfs 7.8G 169M 7.6G 3% /run
tmpfs 7.8G 0 7.8G 0% /sys/fs/cgroup
/dev/mapper/rhel-usr 9.3G 1.4G 8.0G 15% /usr
/dev/mapper/rhel-var 81G 1019M 80G 2% /var
/dev/mapper/rhel-home 19G 1002M 18G 6% /home
tmpfs 1.6G 0 1.6G 0% /run/user/1000

Good - we can see that you use LVM.

What we don't see is whether there is still room on the hard disk, or in the volume group. The output of fdisk -l and vgs will help us understand that.

Thanks for your help. Vendor says that /var can be reduced to 20GB and allocate the remaining to their application partition.

[root@BDOULXXXX tmp]# fdisk -l

Disk /dev/sda: 146.8 GB, 146780121600 bytes, 286679925 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 262144 bytes
Disk label type: dos
Disk identifier: 0x000934d4

Device Boot Start End Blocks Id System
/dev/sda1 * 2048 39063551 19530752 83 Linux
/dev/sda2 39063552 286679039 123807744 8e Linux LVM

Disk /dev/mapper/rhel-swap: 9999 MB, 9999220736 bytes, 19529728 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 262144 bytes


Disk /dev/mapper/rhel-usr: 9999 MB, 9999220736 bytes, 19529728 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 262144 bytes


Disk /dev/mapper/rhel-home: 20.0 GB, 20002635776 bytes, 39067648 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 262144 bytes


Disk /dev/mapper/rhel-var: 86.8 GB, 86763372544 bytes, 169459712 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 262144 bytes

[root@BDOULXXXX tmp]# vgs
VG #PV #LV #SN Attr VSize VFree
rhel 1 4 0 wz--n- 118.07g 12.00m

This indicates that there is practically no free space in the volume group:
This indicates that you are wasting a lot of space for the root filesystem:
but it's not easy to change this.

If you or your vendor think that /var can be, say, 15GB, you could just

• include /var in the root filesystem, i.e. not give it a different filesystem
• use /dev/mapper/rhel-var for your application (I think LVM allows renaming volumes, too).

Or do as I suggested above - boot into single-user mode, resize the /var filesystem, resize the /var volume, then create a new volume from the freed-up space.

I might have given the wrong details for the server. This is the correct server details for the /var that I want to resize.

[root@BDOULXYYYY ~]# df -h
Filesystem Size Used Avail Use Mounted on
/dev/sdb2 19G 1.2G 18G 7% /
devtmpfs 16G 0 16G 0% /dev
tmpfs 16G 0 16G 0% /dev/shm
tmpfs 16G 281M 16G 2% /run
tmpfs 16G 0 16G 0% /sys/fs/cgroup
/dev/mapper/rhel00-usr 9.4G 1.3G 8.1G 14% /usr
/dev/sdb3 782G 1.2G 781G 1% /var
/dev/mapper/rhel00-home 19G 1.9G 17G 10% /home
tmpfs 3.2G 0 3.2G 0% /run/user/1000

[root@BDOULXYYY ~]# vgs
VG #PV #LV #SN Attr VSize VFree
rhel 1 4 0 wz--n- 1.07t 12.00m
rhel00 1 3 0 wz--n- 37.26g 8.00m

[root@BDOULXYYY ~]# fdisk -l

Disk /dev/sdb: 899.9 GB, 899899242496 bytes, 1757615708 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 786432 bytes
Disk label type: dos
Disk identifier: 0x00092631

Device Boot Start End Blocks Id System
/dev/sdb1 1536 78154751 39076608 8e Linux LVM
/dev/sdb2 * 78154752 117216767 19531008 83 Linux
/dev/sdb3 117216768 1757611007 820197120 83 Linux

Disk /dev/sda: 1199.9 GB, 1199865640960 bytes, 2343487580 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 524288 bytes
Disk label type: dos
Disk identifier: 0x0004fdbf

Device Boot Start End Blocks Id System
/dev/sda1 * 2048 39063551 19530752 83 Linux
/dev/sda2 39063552 2343487487 1152211968 8e Linux LVM

Disk /dev/mapper/rhel00-usr: 9999 MB, 9999220736 bytes, 19529728 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 786432 bytes


Disk /dev/mapper/rhel00-swap: 9999 MB, 9999220736 bytes, 19529728 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 786432 bytes


Disk /dev/mapper/rhel00-home: 20.0 GB, 20002635776 bytes, 39067648 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 786432 bytes


Disk /dev/mapper/rhel-home: 20.0 GB, 20002635776 bytes, 39067648 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 524288 bytes


Disk /dev/mapper/rhel-usr: 9999 MB, 9999220736 bytes, 19529728 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 524288 bytes


Disk /dev/mapper/rhel-swap: 9999 MB, 9999220736 bytes, 19529728 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 524288 bytes


Disk /dev/mapper/rhel-var: 1139.8 GB, 1139848249344 bytes, 2226266112 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 262144 bytes / 524288 bytes