Quick Guide to VCF Automation for VCD Administrators

VMware Fixed and Round Robin are two types of path selection policies used in VMware ESXi for multipathing.

Fixed Path Policy:

1. Definition: The Fixed path policy is a path selection policy that always uses the same preferred path for I/O operations.

2. How it works: The ESXi host selects a preferred path for I/O operations and sticks to it unless the path becomes unavailable.

3. Advantages: Provides predictable performance and is suitable for environments where the storage array is configured for active-passive mode.

4. Disadvantages: May not provide optimal performance if the preferred path becomes congested.

Round Robin Path Policy:

1. Definition: The Round Robin path policy is a path selection policy that distributes I/O operations across all available paths in a cyclical manner.

2. How it works: The ESXi host selects a path for I/O operations and then switches to the next available path for the next I/O operation.

3. Advantages: Provides load balancing across all available paths, which can improve performance and reduce the risk of path congestion.

4. Disadvantages: May not provide predictable performance and can be affected by differences in path latency.

When to use each:

1. Fixed Path Policy: Use in environments where predictability and consistency are more important than load balancing, such as in active-passive storage array configurations.

2. Round Robin Path Policy: Use in environments where load balancing and performance are critical, such as in active-active storage array configurations.

Configuration:

To configure the path selection policy in ESXi:

1. Log in to the vSphere Client.

2. Select the ESXi host.

3. Click on "Configuration" and then "Storage".

4. Select the storage device.

5. Click on "Properties" and then "Path Selection Policy".

6. Select the desired path selection policy (Fixed or Round Robin).