In VMware vSphere, there are three different disk provisioning types you can choose when creating a virtual machine, each with different performance and space management:
Thick Provision Lazy Zeroed
When this type is selected, the created disk is allocated a fixed size (e.g., 200GB), but the data space on the disk is gradually zeroed out. For example, when 50GB is actually used, only that 50GB will be zeroed, and the remaining 150GB will be zeroed only when it is used. While this approach saves initial creation time, disk performance suffers because of the additional zeroing operations that may occur during use.
Thick Provision Eager Zeroed
With this type, the entire space of the disk (e.g. 200GB) is zeroed out at the time of creation. Although it takes longer to create the disk, this allows the disk to perform optimally in terms of performance because the entire disk space is fully provisioned before it is used, without introducing additional zeroing delays in subsequent operations.
Thin Provisioning
When Thin Provisioning is selected, the disk is not allocated the full 200GB of space immediately upon creation, but rather the space is incrementally added as the actual data grows. At first, the virtual machine may only take up a small amount of space, and the disk space is gradually expanded as data increases. Although this approach saves disk space initially, it can easily lead to the problem of insufficient space for the entire storage pool, and thus requires special attention in resource management.
Performance Ranking: Thick Provisioning Zero > Thick Provisioning Delayed Zero > Thin Provisioning
Thick provisioning provides the best performance because all provisioning operations are completed at creation time. Thick provisioning with delayed zeroing, on the other hand, processes only a portion of the data at the time of creation, resulting in slightly lower performance. Thin provisioning saves space, but runs the risk of running out of disk space and has the worst performance.
Conclusion
In VMware vSphere, Thick Provision Eager Zeroed offers the best performance with complete zeroing at creation, while Thick Provision Lazy Zeroed provides moderate performance with delayed zeroing. Thin Provisioning saves space but risks performance and space issues.