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What is the vSAN failure domain? How is the vSAN failure domain configured? Generally speaking, people's understanding of vSAN fault domain may stay at the conceptual level, but there is relatively little knowledge about the configuration of vSAN fault domain. Today I will talk to you about the configuration of the vSAN failure domain.

I. Overview of vSAN fault domain

The vSAN fault domain can isolate ESXi hosts.

Consider the following vSAN environment, where there are five ESXi hosts. Physically, servers An and B are located on a rack or a blade server, and servers C, D and E are located on another rack or another blade server. Because the vSAN stores virtual machine components randomly, it is possible to store two components (RAID-1) on servers An and B or servers C and E.

In this way, if the rack where servers An and B are located fails as a whole or the entire blade server fails, the two components of the virtual machine object will be inaccessible and the virtual machine will fail.

In the same way, this happens if the components are stored on C and E.

So, if there is a method or means to store the two components of the virtual machine on rain An and C respectively, then even if this happens, the virtual machine can still be used.

The failure domain of vSAN is the means to solve this situation. In the same vSAN cluster, servers An and B can be defined in one fault domain, and servers C, D and E are defined in another fault domain. Then when vSAN stores virtual machine hosts, it will not store components on hosts in the same fault domain, so as to avoid the above situation.

In the above example, vSAN does not store the components of the virtual machine on servers An and B at the same time, but only on hosts such as An and C, An and C, so that the virtual machine is no longer available in the event of a rack or entire blade server failure.

When a failure domain is enabled in vSAN, at least three failure domains are required, at least one ESXi host in each failure domain, and one witness of two components of RAID-1 under the default storage policy is stored on the host in each of the three failure domains.

It is officially recommended to create at least 4 failure domains. In order to meet more storage policies, more hosts are needed, and there is more than one host in a failure domain.

Second, configure vSAN fault domain

1. Enable the failure domain

2. Create a failure domain FaultDom-01

3. Create 2 more FaultDom-02 and FaultDom-03

4. Adjust virtual machine settings

Once such a failure domain is established, vSAN will not put two components of the same object on two hosts in the same failure domain, such as on 10.8.20.31 and 10.8.20.32.

Go to the virtual machine home page to see storage policy compliance and find that previously created virtual machines are no longer compliant.

First clone a default storage policy and name it "vSAN default storage policy"

Then check and edit the storage policy of the virtual machine

Change the storage policy to vSAN default storage policy

You can see that it becomes "compliance".

Then go to the vSAN monitor to check its physical placement.

It is found that the three components are in three failure domains.

Indicates that the failure domain has played a role.

This is the end of the configuration of the vSAN failure domain. I hope the above content can be helpful to you and learn more knowledge. If you think the article is good, you can share it for more people to see.

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