Create iSCSI storage with MPIO: procedure.

Objective

Present an iSCSI LUN to Windows Server with MPIO by separating storage paths, enabling the Microsoft DSM, creating multiple persistent sessions, configuring multipath policy, and testing the loss of one path.

Do not edit VMDK, AVHDX, cluster or storage metadata manually without a verified backup and a vendor-supported recovery path.
Record VM power state, datastore free space and current snapshot/checkpoint relationships before changing them.
Record the current state before making a production change and keep a tested rollback path.
Change one variable at a time. Preserve timestamps, logs and configuration evidence so the result can be explained afterward.
Use a pilot scope whenever possible and avoid broad service restarts, policy relaxations or destructive cleanup as a first diagnostic step.

Prerequisites

Administrative access to the hypervisor or management plane and a current inventory of affected VMs.
Enough storage and capacity headroom for consolidation, migration, clone or rollback operations.
Administrative access appropriate to the system being changed or diagnosed.
A clearly identified scope: affected users, systems, addresses, services and the time of the observed problem.
A maintenance or test window when the procedure can affect production traffic or availability.
A copy of the current configuration or other recovery material before any irreversible action.

Step-by-step procedure

Establish the baseline and scope

Before changing anything, reproduce the issue or document the requested change on a representative system. Record the affected users or services, exact time, current configuration, recent changes and a known-good comparison point. This baseline is the reference used to decide whether each later step improves the situation.

The scope and current state are documented well enough to reproduce or verify the procedure.

MPIO by separating storage paths

Implement this requirement in a controlled scope: MPIO by separating storage paths. Capture the previous value or configuration first, make the smallest change that satisfies the design, and validate the effective state rather than assuming that a saved setting is active. If the expected result is not obtained, stop, restore the previous state, and reassess before expanding the change.

Evidence for this area is explicit, reproducible and consistent with the intended design.

The Microsoft DSM

Implement this requirement in a controlled scope: the Microsoft DSM. Capture the previous value or configuration first, make the smallest change that satisfies the design, and validate the effective state rather than assuming that a saved setting is active. If the expected result is not obtained, stop, restore the previous state, and reassess before expanding the change.

Evidence for this area is explicit, reproducible and consistent with the intended design.

Creating multiple persistent sessions

Implement this requirement in a controlled scope: creating multiple persistent sessions. Capture the previous value or configuration first, make the smallest change that satisfies the design, and validate the effective state rather than assuming that a saved setting is active. If the expected result is not obtained, stop, restore the previous state, and reassess before expanding the change.

Evidence for this area is explicit, reproducible and consistent with the intended design.

Configuring multipath policy

Implement this requirement in a controlled scope: configuring multipath policy. Capture the previous value or configuration first, make the smallest change that satisfies the design, and validate the effective state rather than assuming that a saved setting is active. If the expected result is not obtained, stop, restore the previous state, and reassess before expanding the change.

Evidence for this area is explicit, reproducible and consistent with the intended design.

The loss of one path

Implement this requirement in a controlled scope: the loss of one path. Capture the previous value or configuration first, make the smallest change that satisfies the design, and validate the effective state rather than assuming that a saved setting is active. If the expected result is not obtained, stop, restore the previous state, and reassess before expanding the change.

Evidence for this area is explicit, reproducible and consistent with the intended design.

Validate the complete service

Repeat the original user, system or application workflow from the real source and verify the complete result, not only one command or one local check. Confirm that logs and monitoring show the expected behavior and that no temporary debug, bypass, test account, rule or maintenance setting remains enabled.

The end-to-end service works or the remaining failure is isolated to a clearly identified component.

Technical commands from the original procedure

These technical blocks are preserved byte-for-byte from the historical procedure and kept in their original order. Review names, addresses, paths and parameters before use.

Technical block 1

Get-NetAdapter

Technical block 2

Get-NetIPConfiguration

Technical block 3

Get-NetIPInterface | Sort-Object InterfaceMetric

Technical block 4

Install-WindowsFeature Multipath-IO

Technical block 5

Get-WindowsFeature Multipath-IO

Technical block 6

Enable-MSDSMAutomaticClaim -BusType "iSCSI"

Technical block 7

Get-MSDSMAutomaticClaimSettings

Technical block 8

Set-Service MSiSCSI -StartupType Automatic

Technical block 9

Start-Service MSiSCSI

Technical block 10

Get-InitiatorPort

Technical block 11

New-IscsiTargetPortal -TargetPortalAddress "<TARGET-IP-1>" -InitiatorPortalAddress "<ISCSI-IP-1>"

Technical block 12

New-IscsiTargetPortal -TargetPortalAddress "<TARGET-IP-2>" -InitiatorPortalAddress "<ISCSI-IP-2>"

Technical block 13

Get-IscsiTargetPortal

Technical block 14

Get-IscsiTarget

Technical block 15

Connect-IscsiTarget -NodeAddress "<TARGET-IQN>" -IsPersistent $true -IsMultipathEnabled $true

Technical block 16

Get-IscsiSession

Technical block 17

mpclaim -s -d

Technical block 18

Get-Disk

Technical block 19

Get-MSDSMSupportedHW

Technical block 20

Initialize-Disk -Number <DISK-NUMBER> -PartitionStyle GPT

Technical block 21

New-Partition -DiskNumber <DISK-NUMBER> -UseMaximumSize -AssignDriveLetter | Format-Volume -FileSystem NTFS -NewFileSystemLabel "<LABEL>" -Confirm:$false

Technical block 22

Get-IscsiSession

Technical block 23

mpclaim -s -d

Validation

The procedure is validated when:

The original symptom or change request has been tested end to end.
The effective configuration matches the intended design and no unexplained error remains in the relevant logs.
Temporary troubleshooting controls have been removed and monitoring remains normal.
The result, evidence and any follow-up action are documented.

Rollback

Restore the configuration, policy, binding, route, credential assignment or service state recorded in the baseline when the change does not meet its success criteria.
Remove temporary rules, test objects and diagnostic settings that were introduced only for the procedure.
After rollback, repeat the minimum health checks to confirm that the previous service level has been restored.

Troubleshooting / common errors

Distinguish a management-plane display issue from an actual disk-chain or storage problem.
When a migration or merge stalls, verify storage latency, free space and task logs before forcing a restart.
If the result changes between tests, compare source, destination, identity, time and policy context before changing additional settings.
If a command succeeds but the application still fails, continue at the next protocol or application layer instead of widening access.
If the expected evidence is missing, verify that logging, auditing and the test path actually cover the failing component.
If the change does not improve the measured symptom, restore the previous state and reassess the working hypothesis.

Official and vendor references preserved from the original procedure

https://learn.microsoft.com/en-us/powershell/module/mpio/enable-msdsmautomaticclaim
https://learn.microsoft.com/en-us/powershell/module/mpio/get-msdsmautomaticclaimsettings
https://learn.microsoft.com/en-us/powershell/module/iscsi/new-iscsitargetportal

Adapt names, addresses, paths and parameters to your environment. Back up the configuration and test on a limited scope first.