This sub-type of thick-provisioned virtual disk supports clustering features, such as fault tolerance.įor data security reasons, eager zeroing is more common than lazy zeroing with thick-provisioned virtual disks. Creating eager zeroed disks takes longer, because zeroes are written to the entire disk, but their performance is faster during the first writes. An Eager zeroed disk is a disk that gets all of the required space still at the time of its creation, and the space is wiped clean of any previous data on the physical media.This type of disk can be created more quickly, but its performance will be lower for the first writes due to the increased IOPS (input/output operations per second) for new blocks This old data is not erased or written over, so it needs to be 'zeroed out' before new data can be written to the blocks. A Lazy zeroed disk is a disk that takes all of its space at the time of its creation, but this space may contain some old data on the physical media.There are two sub-types of thick-provisioned virtual disks: A thick-provisioned virtual disk consumes all the space allocated to it in the datastore right from the start, so the space is unavailable for use by other virtual machines. With thick provisioning, the complete amount of virtual disk storage capacity is pre-allocated on the physical storage when the virtual disk is created. Thick provisioning is a type of storage pre-allocation.

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