[What's the Difference] Thin Provision VS Thick in VMware

Rel updated on Jan 11, 2024 | Home > Knowledge Center

Thin provisioning and thick provisioning are available storage pre-allocation schemes when creating VMware virtual machines. Although they can allocate the storage of virtual disks, they are fundamentally different.

What Is Thin Provision

Thin provision is the fastest way to pre-allocate storage. At first, it will only allocate the necessary storage for the VM and then use the available dynamic space to meet the growing storage needs continuously.

thin provision

Thin Provision Features

The following are its characteristics:

  • The creation time is the fastest, but the first write time is still required
  • Allow over configuration
  • Effectively save space
  • Has to write zeroes before writing data to a new block
  • When data is deleted, the disk size will not decrease automatically

What Is Thick Provision

Thick Provision is another storage pre-allocation scheme that is as important as thin provision. Unlike the dynamic storage method adopted by the thin provision, the thick provision will pre-allocate fixed physical storage to the VM when creating virtual disks. These virtual disks will consume all the space allocated to them from the beginning so that other virtual machines cannot use this space.

This also means that if you create a 50GB virtual disk using the thick Provision, it will actually consume 50GB of physical disk space. Even if no data is written to the disk later, this physical storage cannot be occupied by other data.

thick provision

Types of Thick Provision

Thick Lazy Zeroed:

  • Use the actual physical storage to create a virtual machine, but it will contain the previous old data. When new data is written for the first time, these old data will be cleared. This type of thick configuration can be created quickly, but due to the increased Input/Output operations per second for a new block, the first write speed will be very slow.

Thick Eager Zeroed:

  • Use all the space to create a virtual machine and clean up the old data before writing new data. Contrary to the performance of Thick Lazy Zeroed, the creation speed of Thick Eagle Zeroed is slow, but the first write speed is fast.

What Is the Difference between Thin and Thick Provision

Thin provision and thick provision are very different in 4 aspects: Storage changes, creation time, first write speed, and over-provisioning.

Comparison Thin Provision Thick Lazy Zeroed Thick Eager Zeroed
Storage Changes  Yes No No
Creation Time Shortest Short Longest
First Write   Slowest Fast Fastest  


Yes No No


Each storage pre-allocation scheme has its advantages and disadvantages at the same time. Thin Provision is the most space-saving choice when creating virtual disks, and the creation time is very short too. But it requires a high level of monitoring to ensure data security. Thick Eagle Zeroed has good performance and is relatively safe, but it requires high storage space and takes a long time to create. The creation time of Thick Lazy Zeroed is short, but the writing speed and security are not as good as that of Thick Eagle Zeroed.

To sum up, when you choose the storage pre-allocation scheme, please refer to the actual situation and make a satisfactory choice.

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Updated by Daisy

Daisy is the Senior editor of the writing team for EaseUS. She has been working at EaseUS for over ten years, starting as a technical writer and moving on to being a team leader of the content group. As a professional author for over ten years, she writes a lot to help people overcome their tech troubles.

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Written by Rel

Rel has always maintained a strong curiosity about the computer field and is committed to the research of the most efficient and practical computer problem solutions.

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