A virtualization administrator configures three new VM virtual disks on a single host that has 1TB (1000GB) of physical storage installed. Each VM is assigned a 500GB virtual disk, and the administrator confirms only 300GB of actual data currently exists across all three VMs combined. Which storage technology allows this configuration to exist safely, and what must the administrator actively monitor going forward?
- AThick provisioning; monitor CPU core allocation to prevent oversubscription
- BThin provisioning; monitor actual physical storage consumption to prevent the datastore from filling up
- CRAID 0 striping; monitor read/write latency to avoid disk failure
- DStorage tiering; monitor which VMs are using SSD versus HDD tiers
Show answer & explanationAnswer & explanation
Correct answer: B. Thin provisioning; monitor actual physical storage consumption to prevent the datastore from filling up
Thin provisioning allocates virtual disk space on demand rather than reserving it all upfront, so three 500GB virtual disks (1500GB allocated) can exist on only 1000GB of physical storage as long as actual used data stays below capacity (here, 300GB). Because allocated capacity (1500GB) exceeds physical capacity (1000GB), an overcommit ratio of 1.5:1 exists, so the admin must monitor real usage to avoid running out of physical space as data grows.
Why the other options are wrong
- A. Thick provisioning reserves the full 500GB per disk immediately, which would exceed the 1000GB physical limit and fail here.
- C. RAID 0 improves performance/capacity striping but does not explain how allocated space can exceed physical capacity.
- D. Storage tiering moves data between fast and slow disks based on access frequency, unrelated to overcommitted capacity.
Thin Provisioning / Storage Overcommit
A storage allocation method where virtual disks are assigned a maximum size but only consume physical storage as data is actually written, allowing total allocated space to exceed physical capacity.
- Allocated capacity can exceed physical capacity (overcommit)
- Requires ongoing monitoring to avoid the datastore filling up
- Opposite of thick provisioning, which reserves full space upfront
Memory trick: Thin provisioning is like overbooking a flight — fine until everyone shows up.