Making an iSCSI target persistent with PowerShell

One of the iSCSI targets in my homelab began to not automatically reconnect after reboots, for unknown reason(s). This quick-tip post shows how to remedy it.

Symptoms

After the latest Patch Tuesday my server didn’t reconnect a particular iSCSI target.

iSCSI Initiator Properties - Targets

Being a designated favorite target it should have at least attempted a reconnect.

iSCSI Initiator Properties - Favorite targets

Troubleshooting

There’s no “persistence” flag in the UI for iSCSI; in theory every favorited target should be persistent by default, and this has worked for a couple of years with the target in question. No matter why it fell out of “persistence grace”, I turned to PowerShell in my troubleshooting efforts.

The Get-IscsiSession cmdlet, a wrapper for the MSFT_iSCSISession class, shows the current iSCSI sessions - excluding my favorite that didn’t successfully connect.

Get-IscsiSession

I connected the session in iSCSI Initiator Properties manually to have a look at the properties.

iSCSI Initiator Properties - Connect to Target

Get-IscsiSession

AuthenticationType      : NONE
InitiatorInstanceName   : ROOT\ISCSIPRT\0000_0
InitiatorNodeAddress    : iqn.1991-05.com.microsoft:lab
InitiatorPortalAddress  : 0.0.0.0
InitiatorSideIdentifier : 400001370000
IsConnected             : True
IsDataDigest            : False
IsDiscovered            : False
IsHeaderDigest          : False
IsPersistent            : False
NumberOfConnections     : 1
SessionIdentifier       : ffffc8094f9d7010-40000213800000009
TargetNodeAddress       : iqn.2004-04.com.qnap:ts-664:iscsi.files.8c8fe8
TargetSideIdentifier    : 2400

Pressingly the session’s properties states that IsPersistent is false, meaning that it won’t re-establish commerece, as it were, on reboots.

There’s another cmdlet, Register-IscsiSession, a wrapper for the MSFT_iSCSISession class’ Register method, that makes sessions persistent.

Since I only have one session, I could do:

Get-IscsiSession | Register-IscsiSession

Otherwise filter by e.g. the TargetNodeAddress property which correlates with the target name in iSCSI Initiator Properties.

Get-IscsiSession | Where-Object { $_.TargetNodeAddress -eq 'iqn.2004-04.com.[..]' }

However, the IsPersistent flag was still showing non-persistence.

Resolution

What ultimately worked was running the Unregister-IscsiSession cmdlet first (another option might’ve been to remove the target and recreating it):

Get-IscsiSession | Unregister-IscsiSession

Get-IscsiSession | Register-IscsiSession

At which point the property gleamed True.

After a reboot, the iSCSI target now connects every time!

.NET class

To instead use the underlying .NET class directly, access the class with Get-CimInstance and the register- and unregister methods with Invoke-CimInstance:

$session = Get-CimInstance -ClassName 'MSFT_iSCSISession' -Name 'Root\Microsoft\Windows\Storage'

Invoke-CimMethod -InputObject $session -MethodName Unregister

ReturnValue PSComputerName
----------- --------------
          0

Invoke-CimMethod -InputObject $session -MethodName Register -Arguments @{ 'IsMultipathEnabled' = $false }

ReturnValue PSComputerName
----------- --------------
          0

Credits

Some photos showcasing Microsoft technology. Featured image from episode 3 of season 3 of TV series Silicon Valley.