6.0.1

2 Unmount the datastore.
See “Unmount Datastores,” on page 168.
3 Perform a rescan on all ESXi hosts that had access to the device.
See “Perform Storage Rescan,” on page 125.
N If the rescan is not successful and the host continues to list the device, some pending I/O or active
references to the device might still exist. Check for virtual machines, templates, ISO images, raw device
mappings, and so on that might still have an active reference to the device or datastore.
Handling Transient APD Conditions
A storage device is considered to be in the all paths down (APD) state when it becomes unavailable to your
ESXi host for an unspecied period of time.
The reasons for an APD state can be, for example, a failed switch or a disconnected storage cable.
In contrast with the permanent device loss (PDL) state, the host treats the APD state as transient and expects
the device to be available again.
The host indenitely continues to retry issued commands in an aempt to reestablish connectivity with the
device. If the host's commands fail the retries for a prolonged period of time, the host and its virtual
machines might be at risk of having performance problems and potentially becoming unresponsive.
To avoid these problems, your host uses a default APD handling feature. When a device enters the APD
state, the system immediately turns on a timer and allows your host to continue retrying nonvirtual machine
commands for a limited time period.
By default, the APD timeout is set to 140 seconds, which is typically longer than most devices need to
recover from a connection loss. If the device becomes available within this time, the host and its virtual
machine continue to run without experiencing any problems.
If the device does not recover and the timeout ends, the host stops its aempts at retries and terminates any
nonvirtual machine I/O. Virtual machine I/O will continue retrying. The vSphere Web Client displays the
following information for the device with the expired APD timeout:
n
The operational state of the device changes to Dead or Error.
n
All paths are shown as Dead.
n
Datastores on the device are dimmed.
Even though the device and datastores are unavailable, virtual machines remain responsive. You can power
o the virtual machines or migrate them to a dierent datastore or host.
If later one or more device paths becomes operational, subsequent I/O to the device is issued normally and
all special APD treatment ends.
Disable Storage APD Handling
The storage all paths down (APD) handling on your ESXi host is enabled by default. When it is enabled, the
host continues to retry nonvirtual machine I/O commands to a storage device in the APD state for a limited
time period. When the time period expires, the host stops its retry aempts and terminates any nonvirtual
machine I/O. You can disable the APD handling feature on your host.
If you disable the APD handling, the host will indenitely continue to retry issued commands in an aempt
to reconnect to the APD device. Continuing to retry is the same behavior as in ESXi version 5.0. This
behavior might cause virtual machines on the host to exceed their internal I/O timeout and become
unresponsive or fail. The host might become disconnected from vCenter Server.
Chapter 13 Managing Storage Devices
VMware, Inc. 129