Hi Shafi,

Creating a thin provisioned disk using a block Storage Domain will allocate 512MB of disk space. I don’t have the values for a file-based Storage Domain.

In a regular VM operation, the disk is increased when it reaches 80% (dev team, correct me if I’m wrong) of the allocated space used. This does not impact the VM operation, and disks are increased as needed with no VM downtime.

If you try to test this disk size-increasing functionality using tools like dd, you will fail because it does not behave like a normal VM operation.

Regards,

Marcos

From: Shafi Mohammed <shafiontherise@gmail.com>
Sent: Friday, March 22, 2024 3:53 AM
To: users@ovirt.org
Subject: [External] : [ovirt-users] Understanding Preallocation (Actual) Size of a thin DIsk

HI ,

I need to know about the Pre allocation size of a thin disk while creating a disk in a storage domain .

Can we change the  actual size (allocated Size ) after disk creation .Can anyone can enlighten me on how it will increase when the size of the disk exceeds the allocated limit ?

If I try to write to the disk from the hypervisor , the write gets failed after the allocated size whereas if i create a thick disk i am able to write till the disk capacity 



Regards
Shafi