Learn what to do if APD timeout is disabled from our experts. Our VMware Support team is here to help you with your questions and concerns.

APD timeout is disabled | Resolved

Did you know that in VMware ESXi environments APD situations can occur when all paths to a storage device become unavailable?

APD, short for All Paths Down, can impact the availability of data stores and virtual machines. In other words, it can lead to unresponsiveness or failure.

Today, we are going to take a close look at APD situations, their causes, and the steps to handle them in VMware ESXi.

By default, ESXi hosts are configured with APD handling enabled. When an APD state is detected, the host retries non-virtual machine I/O commands to the storage device for a certain time period. After this time period, the host terminates all remaining I/O attempts.

When we disable APD handling, it will cause the host to indefinitely retry commands, thereby exceeding the internal I/O timeout of Vms. This leads to unresponsiveness or failure.

How to disable APD Handle

1. First, we have to launch the vSphere Client and head to the ESXi host.
2. Then, click the Configure tab and choose Advanced System Settings under the System section.
3. Now, we have to locate the “Misc.APDHandlingEnable” parameter and click the edit icon.
4. Next, we have to change the value of the parameter to “0” to disable APD handling and then Save the changes.

Our experts would like to point out that disabling APD handling should be done with caution. With APD handling disabled, the host will continue indefinitely attempting to reconnect to the APD device, causing VMs to exceed their internal I/O timeouts and become unresponsive or fail. Additionally, the host may become disconnected from vCenter Server.

How to Resolve APD Situations

1. First, we have to check the storage array, SAN switch, and other components to identify the cause of the disconnected LUNs.
2. Then, take actions to address the cause of the APD situation, like fixing failed switches or reconnecting storage cables.
3. Next, it is time to remove any residual references to devices in the APD state.
4. Finally, check if the Vms on the affected data stores are still responsive.

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Conclusion

In summary, our Support Techs demonstrated how to proceed when APD timeout is disabled.