Increasing the drive size, does Not increase the partition. Some additional steps in each case.

I found I had to boot a GParted ISO to do the root partition.  But do make sure you have a full image backup before doing this. 

get the root partition issues sorted out first. How big is it currently and what are you aiming for?

for NSS -
 - use iManager (storage role) to grow the pool size first, up to the 2TB limit you have at that version level.  Only once that is done can you grow the volume.  If you are going beyond the 2TB level, say so as we can get a volume as big as 8TB

for further details, we will need to know which virtualisation you are running.

I am using KVM virtualization. My data disk size is 800GB. I increased the size of this to 900GB using qemu-img command. But after rebooting it is not showing the increased size (with unallocated region) So I cannot use iManager to grow the pool. I tried this on another test sever. There the disk type was MSDOS, here it shows the increased size of attached disk as unallocated. Then I can use nssmu to expand the pool.

Would GParted live help in increasing the size of disk?

Regards,

What is "it" when you say "it is not showing the increased size". Which tool do you use to check the disk size?
And, please, do not use imanager to manipulate disks. Use nssmu only.

I use yast2 disk (partitioner) to see the hard disks and partitons. One thing I noticed is that in a test server with GPT type hard disk, resizing using qemu-img command shows the increased size, so it does not seem to be problem with GPT type partitions. Is there any limit after which we cannot grow the disk size? Current size is 800GB. I might just add another disk and create another pool/volumes in it.

Sorry for stating the obvious, but the obvious answer is that your hypervisor did *not* extend the disk. or you did not reboot the guest. That's basically the only two serious options.

I rebooted the guest but still partitioner does not show the unallocated space. fdisk does not have -x option in my OS. Also "parted" is showing disk size as 850GB instead of 900GB. Anyhow, I am going to add another disk create another pool and move the volumes from the existing pool. Thanks everyone for your help.

I rebooted the guest but still partitioner does not show the unallocated space. fdisk does not have -x option in my OS. Also "parted" is showing disk size as 850GB instead of 900GB. Anyhow, I am going to add another disk create another pool and move the volumes from the existing pool. Thanks everyone for your help.