Question about VM vmdk file sizes vs data actually used on the VM

[Soundwave2019]

Good afternoon,

I have a RHEL server. Today I logged in and saw /dev/mapper/rhel-root was at 91% utilization. I decided to add a disk of 500GB. I have an existing disk of 500GB. In the process of figuring out how to get RHEL to recognize the new disk, I noticed something odd. The guest OS reports 91% utilization. However when I check vCenter both thru vmware workstation and the vCenter web portal I can see that the original 500GB hard drive is 10GB in size.

Where is the discrepancy occurring?

The VMDK files are thin provisioned, and stored with the VM on the datastore. Space has not been pre-allocated for these disks.

Have I just messed up in allocating the space in the guest OS file system?

[StephenMoll]

Have you checked that the OS file system partitions are sized correctly?

Does "df -H" show all the partitions and sizes you expect for the size of the virtual disk provided.

It is possible the "root" partition holding "/dev/mapper/rhel-root" is only 10GB of the whole virtual drive, and is the only partition at 91% utilised. The "home" partition or whatever it is called is likely the bulk of the 500GB and mostly empty. This might have arisen from a 'minimal' install being selected when the VM was created.

[CMS201110141]

As StephenMoll already mentionend there may be still free space that's just not yet assigned to your filesystems.

You can try lsblk and vgdisplay -v to figure out more details of the disk configuration.