6.5

Table Of Contents
Reattach a Device
When you have completed storage reconguration, you can reaach the storage device, mount the
datastore, and restart the virtual machines.
Prerequisites
Make sure you are familiar with datastore mounting. See“Mounting Datastores with Existing Signatures,”
on page 32.
Procedure
1 (Optional) Check whether the device is detached.
esxcli storage core device detached list
2 Aach the device.
esxcli storage core device set -d naa.XXX --state=on
3 Mount the datastore and restart virtual machines.
Working with Permanent Device Loss
In some cases a permanent device loss (PDL) might occur.
With earlier ESXi releases, an APD (All Paths Down) event results when the LUN becomes unavailable. The
event is dicult for administrators because they do not have enough information about the state of the LUN
to know which corrective action is appropriate.
In ESXi 5.0, the ESXi host can determine whether the cause of an APD event is temporary, or whether the
cause is PDL. A PDL status occurs when the storage array returns SCSI sense codes indicating that the LUN
is no longer available or that a severe, unrecoverable hardware problem exist with it. ESXi has an improved
infrastructure that can speed up operations of upper-layer applications in a device loss scenario.
I Do not plan for APD or PDL events, for example, when you want to upgrade your hardware.
Instead, perform an orderly removal of LUNs from your ESXi server, which is described in “Detach a Device
and Remove a LUN,” on page 48, perform the operation, and add the LUN back.
Removing a PDL LUN
How you remove a PDL LUN depends on whether it was in use.
n
If the LUN that goes into PDL is not in use by any user process or by the VMkernel, the LUN
disappears by itself after a PDL.
n
If the LUN was in use when it entered PLD, delete the LUN manually by following the process
described in “Detach a Device and Remove a LUN,” on page 48.
Reattach a PDL LUN
You can reaach a PDL LUN after it has been removed.
Procedure
1 Return the LUN to working order.
Chapter 4 Managing Storage
VMware, Inc. 49