An administrator runs the command esxcli storage core device list and sees the following output:
mpx.vmhba1:C0:T0:L0 Display Name: RAID 5 (mpx.vmhba1:C0:T0:L0) Has Settable Display Name: false SizE. 40960 Device Type: Direct-Access Multipath
Plugin: NMP Devfs Path:
/vmfs/devices/disks/mpx.vmhba1:C0:T0:L0 Status: off Is Local: true
What can be determined by this output?
A.
The device is a being used for vFlash Read Cache.
B.
The device is in a Permanent Device Loss (PDL) state.
C.
The device is a local Solid State Device (SSD).
D.
The device is in an All Paths Down (APD) state.
Explanation:
Explanation/Reference:
Correct is B.
From the output, it is shown as lost (/vmfs/devices/disks/mpx.vmhba1:C0:T0:L0 Status: off)
Permanent Device Loss (PDL):
A datastore is shown as unavailable in the Storage view
A storage adapter indicates the Operational State of the device as Lost Communication
All-Paths-Down (APD):
A datastore is shown as unavailable in the Storage view.
A storage adapter indicates the Operational State of the device as Dead or Error.
https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2004684
I meant “A storage adapter is shown as lost (/vmfs/devices/disks/mpx.vmhba1:C0:T0:L0 Status: off)”
While ‘B’ is most plausible, there seems to be nothing in the output preventing ‘D’ from being correct too. “Status: off” is not the same as “Lost Communication” and can be due to either “Dead” or “Error”.
The only way to confirm is to review the SCSI Sense codes:
Devices that suffer a non-recoverable hardware error are also recognized as being in a Permanent Device Loss (PDL) state.
This table outlines possible SCSI sense codes that determine if a device is in a PDL state [see table in KB]
https://kb.vmware.com/kb/2004684
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With earlier ESXi releases, an APD (All Paths Down) event results when the LUN becomes unavailable. The event is difficult 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 All Paths Down (APD) event is temporary, or whether the cause is permanent device loss. 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.
https://pubs.vmware.com/vsphere-60/topic/com.vmware.vcli.examples.doc/cli_manage_storage.6.5.html
Status: off means device is offline !