Knowledge Base

Storage in virtual environments is a critical factor that directly affects performance and cost. VMware vSAN and different disk provisioning types, especially Thick Provisioning, offer different approaches to meet the storage requirements of virtual machines. This article aims to help you decide which storage solution is best for you by examining the features, advantages, disadvantages, and usage scenarios of vSAN and Thick disks in detail.

1. Introduction: The Role of Storage and vSAN in Virtualization

Virtualization enables businesses to use hardware resources more efficiently, reduce costs, and make IT infrastructure more flexible. In this context, storage solutions play a critical role in meeting the data storage, access, and backup needs of virtual machines (VMs). Unlike traditional storage solutions, vSAN (Virtual SAN) is a software-defined storage (SDS) solution developed by VMware. vSAN aggregates the local storage resources of servers to create a shared storage pool. This provides a high-performance and scalable storage infrastructure without the need for separate storage hardware (SAN or NAS).

Thick Provisioning, on the other hand, is a method of pre-allocating storage space for virtual disks. While this approach offers performance advantages, it may provide less flexibility in storage space utilization. In this article, we will examine in detail how Thick Provisioning is used in vSAN environments and compare it with other storage options.

2. An In-Depth Look at vSAN

2.1. Core Components and Architecture of vSAN

vSAN aggregates the local storage devices (SSDs, HDDs) of servers in a vSphere cluster to create a shared storage pool. This pool provides storage space for virtual machines. The vSAN architecture consists of the following core components:

• vSphere Cluster: vSAN runs on a vSphere cluster. Each server in the cluster joins vSAN and shares its storage resources.
• Disk Groups: Each vSAN server can have one or more disk groups. Each disk group contains at least one cache tier (usually SSD) and one capacity tier (SSD or HDD).
• Distributed RAID: vSAN prevents data loss and ensures high availability by distributing data across the cluster. This process is performed using distributed RAID mechanisms (e.g., RAID 1, RAID 5, RAID 6).
• Storage Policies: vSAN uses storage policies to meet the storage requirements of virtual machines. These policies define parameters such as performance, capacity, and availability.

Visual Description: A diagram illustrating the vSAN architecture, visually explaining how servers, disk groups, and distributed RAID work.

2.2. Advantages and Disadvantages of vSAN

vSAN offers several advantages compared to traditional storage solutions:

• High Performance: Provides high IOPS and low latency thanks to SSD caching and distributed RAID.
• Scalability: Storage capacity and performance can be easily increased by adding servers to the cluster.
• Cost Efficiency: Reduces costs as a separate storage hardware is not required.
• Simple Management: Easily manageable as it is integrated with vSphere.
• High Availability: Prevents data loss and provides high availability thanks to distributed RAID.

However, vSAN also has some disadvantages:

• Hardware Compatibility: vSAN has specific hardware requirements. Not all hardware may be compatible with vSAN.
• Licensing Costs: vSAN may bring an additional cost to VMware licensing costs.
• Complexity: Configuring and managing vSAN correctly may require expertise.

2.3. Different Use Cases of vSAN

vSAN can be used effectively in various use cases:

• Virtual Desktop Infrastructure (VDI): Ideal for meeting high performance and low latency requirements.
• Server Virtualization: Suitable for the performance and scalability of workloads.
• Disaster Recovery (DR): Can be used for replicating data to a remote location.
• Remote Office/Branch Office (ROBO): Ideal for providing local storage without the need for a central storage infrastructure.

3. What is Thick Disk (Thick Provisioning)?

3.1. Basic Concepts of Thick Provisioning

Thick Provisioning means that the storage space of a virtual disk is fully allocated at the time of creation. That is, when a disk is created for a virtual machine (VM), the specified amount of storage space is immediately allocated and used. This means that the allocated space is used even if there is no data on the disk.

There are two main types of Thick Provisioning:

• Thick Provision Eager Zeroed: When the disk is created, all storage space is allocated and filled with zeros. This prevents any performance delays before data is written to the disk.
• Thick Provision Lazy Zeroed: When the disk is created, storage space is allocated, but not filled with zeros. During the first data write operation, the relevant blocks are filled with zeros. This speeds up the disk creation process, but may cause performance delays during the first write operations.

3.2. Advantages and Disadvantages of Thick Provisioning

The advantages of Thick Provisioning are:

• Better Performance: Especially Thick Provision Eager Zeroed provides better performance in data writing operations on the disk, because the storage space is pre-allocated and filled with zeros.
• Less Fragmentation: The possibility of disk fragmentation is lower because the storage space is pre-allocated.
• Predictable Storage Usage: It is easier to predict storage usage because the storage space is pre-allocated.

The disadvantages of Thick Provisioning are:

• More Storage Space Usage: Storage space usage is higher because storage space is allocated even if there is no data on the disk.
• Longer Disk Creation Time: Especially Thick Provision Eager Zeroed can extend the disk creation time.
• Less Flexibility: It is more difficult to dynamically increase or decrease storage space because storage space is pre-allocated.

3.3. Usage Scenarios of Thick Provisioning

Thick Provisioning can be preferred in the following scenarios:

• Performance Critical Applications: It is ideal for applications that require high performance.
• Storage Space Planning: It is suitable in cases where storage space usage needs to be known in advance.
• Fragmentation Sensitivity: It can be preferred in cases where disk fragmentation needs to be prevented.

4. vSAN and Thick Disk: Comparison

4.1. Performance Comparison

Using Thick Provisioning in a vSAN environment, especially the Thick Provision Eager Zeroed option, can improve performance. Because the disk space is pre-allocated and filled with zeros, this prevents delays in the first write operations. However, Thin Provisioning can also be used in a vSAN environment and may perform better in some cases. For example, Thin Provisioning offers a more flexible solution in cases where storage space usage changes dynamically.

The following table summarizes the performance comparison between vSAN and Thick Disk:

4.2. Storage Space Usage Comparison

Thick Provisioning uses more storage space because it pre-allocates storage space. Thin Provisioning, on the other hand, uses less storage space because it only allocates storage space as it is used. This can be an important factor when storage capacity is limited.

The following table summarizes the storage space usage comparison between vSAN and Thick Disk:

4.3. Cost Comparison

Thick Provisioning can lead to higher storage costs because it uses more storage space. However, it can provide better performance and make it easier to manage storage space. Thin Provisioning, on the other hand, can lead to lower storage costs because it uses less storage space. However, it can cause performance issues and make storage space more complex to manage.

5. Step by Step: Creating a Thick Disk in vSAN

To create a Thick Disk in a vSAN environment, you can follow these steps:

1. Log in to vSphere Web Client: Log in to vSphere Web Client with your username and password.
2. Create a Virtual Machine or Edit an Existing Virtual Machine: You can create a new virtual machine or edit an existing virtual machine.
3. Configure Virtual Machine Settings: When configuring virtual machine settings, select the "Hard Disk" option.
4. Select Disk Provisioning Type: Select either "Thick Provision Eager Zeroed" or "Thick Provision Lazy Zeroed" as the disk provisioning type.
5. Determine Disk Size: Determine the size of the disk. This size determines the storage space that will be allocated when the disk is created.
6. Create or Edit the Virtual Machine: Create or edit the virtual machine.

Code Example (PowerCLI):

# Creating a Thick Provisioned disk in a vSAN environment

$vmName = "TestVM"
$diskSizeGB = 100
$datastoreName = "vsanDatastore"

New-VM -Name $vmName -Datastore $datastoreName -DiskGB $diskSizeGB -DiskStorageFormat Thick

6. Real-World Examples and Case Studies

Example 1: A financial institution uses vSAN for a database application that requires high transaction volume and low latency. This organization has improved database performance by using the Thick Provision Eager Zeroed option.

Example 2: An e-commerce company uses vSAN for a virtual desktop infrastructure (VDI) with dynamically changing storage needs. This company uses Thin Provisioning to use storage space more efficiently.

Case Study: A healthcare organization uses vSAN to store patient records. This organization uses the Thick Provision Eager Zeroed option to ensure data security and performance. In addition, it prevents data loss by taking advantage of vSAN's high availability features.

7. Frequently Asked Questions (FAQ)

• Question 1: What is the best combination of vSAN and Thick Provisioning?
• Answer: The combination of vSAN and Thick Provision Eager Zeroed is best for applications that require high performance. However, if you want to use storage space more efficiently and have dynamically changing storage needs, the combination of vSAN and Thin Provisioning may be more appropriate.
• Question 2: How does Thick Provisioning affect vSAN performance?
• Answer: Thick Provisioning, especially Thick Provision Eager Zeroed, provides better performance in data write operations on the disk because the storage space is pre-allocated and filled with zeros. This prevents delays in initial write operations.
• Question 3: Can Thin Provisioning be used in a vSAN environment?
• Answer: Yes, Thin Provisioning can be used in a vSAN environment. Thin Provisioning allows you to use storage space more efficiently because it only allocates storage space as it is used. However, it can cause performance issues and make storage space more complex.

8. Conclusion and Summary

vSAN and Thick Disk offer different approaches to meet storage requirements in virtual environments. vSAN, as a software-defined storage solution, provides high performance, scalability, and cost-effectiveness. Thick Provisioning, on the other hand, offers better performance and predictable storage usage by pre-allocating disk space.

In summary:

• vSAN aggregates local storage resources of servers to create a shared storage pool.
• Thick Provisioning means pre-allocating disk space and can provide better performance.
• Thin Provisioning means allocating disk space only as it is used, allowing you to use storage space more efficiently.
• When deciding which storage solution is best for you, you should consider factors such as performance, storage space usage, cost, and ease of management.

In this article, we have examined the features, advantages, disadvantages, and usage scenarios of vSAN and Thick disks in detail. I hope this information helps you choose the most suitable storage solution for your virtual environment.