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,

I have never used or needed GParted for NSS volumes. I'm just used it for the root partition, since as a general rule, the root partition can not be changed while running the OS is running off of it.

As for the expansion working for the old MSDOS partitioning, but not for GPT, that sounds more like an issue at the KVM layers.  I don't yet have any KVM experience outside that older meaning of the term of the physical switches.  If no one else here joins in, you might want to look at KVM focused areas.

Here is where GParted might be useful, just to compare what it sees between the v-drives under both GPT vs your MSDOS test.

I have never used or needed GParted for NSS volumes. I'm just used it for the root partition, since as a general rule, the root partition can not be changed while running the OS is running off of it.

As for the expansion working for the old MSDOS partitioning, but not for GPT, that sounds more like an issue at the KVM layers.  I don't yet have any KVM experience outside that older meaning of the term of the physical switches.  If no one else here joins in, you might want to look at KVM focused areas.

Here is where GParted might be useful, just to compare what it sees between the v-drives under both GPT vs your MSDOS test.