Hard disk problem after increase its size in ubuntu 16_Vsphere6.5

You now also need to increase the size of the OS Partitions in the Guest OS e.g. Ubuntu.

VMware vSphere ESXi 6.5 does not do this.

You've just changed the size of hard drive, not the OS partition.

When you login into your VM as user "administrator", like you did for issuing the commands "df -h" and "ifconfig" above, you will not be able to resize the partition /dev/sda1 since it will be an active partition, which you can't unmount.
So you have to stop the VM, and being sure it will not restart from a snapshot.
Here you will find a step by step description on how to proceed further.

When using GParted to resize the disk, I got this. How can I merge the New Partition 1 to /dev/sda1 ?

You've got to

Remove

1. Extended.
2. SWAP

then expand

sda1...

Or move extended to end of disk, and expand sda1.

e.g. the free space needs to be  ext to /dev/sda1 e.g. contiguous.

Hi Andrew, yes I did it but seems like the swap is not working, although it was configured swapon. Can you please suggest?

Check your /etc/fstab file includes a line containing "swap".

Hi, this is the result in fstab:



one more thing, when I issued command: top -h, it seems like our buff was using quite lot of RAM, was it good?

You have to "§format" a disk as swap disk (i.e. write a "header" to it  marking it as a swap device.

The command to do so is "mkswap"

in your case this would be:
####### write swap signature to the swap partition
$ sudo mkswap /dev/sda2
####### write out buffers to disk - just to be sure
$ sync
####### identify UUID of swap partition and verify it matches the UUID in /etc/fstab
$ sudo blkid
#######  turn on swap on all devices configured in /etc/fstab
$ sudo swapon -a

sudo swapon -a