Windows Server storage: iSCSI, MPIO and Storage Spaces

Start DC01. Shut down SRV01 for now. Work on your laptop first, then on SRV01 and NODE1 in PowerShell as administrator.

1Add a second network and disks

On your laptop, create LabNet2, give SRV01 a second NIC and three small disks:

VBoxManage natnetwork add --netname LabNet2 --network "10.0.1.0/24" --enable --dhcp off
VBoxManage modifyvm SRV01 --nic2 natnetwork --nat-network2 LabNet2
VBoxManage storagectl SRV01 --name SATA --portcount 8
3..5 | ForEach-Object {
    VBoxManage createmedium disk --filename "C:\Lab\VMs\SRV01\SRV01-pool$_.vdi" --size 4096
    VBoxManage storageattach SRV01 --storagectl SATA --port $_ --device 0 --type hdd --medium "C:\Lab\VMs\SRV01\SRV01-pool$_.vdi"
}
VBoxManage startvm SRV01

Create NODE1 with two NICs, then install Server Core on it as in Lesson 33:

VBoxManage createvm --name NODE1 --ostype Windows2025_64 --basefolder C:\Lab\VMs --register --default
VBoxManage modifyvm NODE1 --memory 2048 --cpus 2 --nic1 natnetwork --nat-network1 LabNet --nic2 natnetwork --nat-network2 LabNet2
VBoxManage createmedium disk --filename C:\Lab\VMs\NODE1\NODE1.vdi --size 40960
VBoxManage storageattach NODE1 --storagectl SATA --port 0 --device 0 --type hdd --medium C:\Lab\VMs\NODE1\NODE1.vdi
VBoxManage storageattach NODE1 --storagectl SATA --port 1 --device 0 --type dvddrive --medium C:\Lab\ISO\server2025.iso
VBoxManage startvm NODE1

On SRV01, give the new NIC an address:

Get-NetAdapter | Select-Object Name, InterfaceDescription, Status
New-NetIPAddress -InterfaceAlias 'Ethernet 2' -IPAddress 10.0.1.20 -PrefixLength 24 | Out-Null

On NODE1 (after installing Server Core and choosing 15 in sconfig):

New-NetIPAddress -InterfaceAlias Ethernet -IPAddress 10.0.0.41 -PrefixLength 24 -DefaultGateway 10.0.0.1 | Out-Null
New-NetIPAddress -InterfaceAlias 'Ethernet 2' -IPAddress 10.0.1.41 -PrefixLength 24 | Out-Null
Set-DnsClientServerAddress -InterfaceAlias Ethernet -ServerAddresses 10.0.0.10, 10.0.0.11
Add-Computer -DomainName saatlab.internal -NewName NODE1 -OUPath 'OU=Servers,OU=SAATLAB,DC=saatlab,DC=internal' -Credential SAATLAB\adm.rahul -Restart

The storage network has no gateway or DNS server on purpose: it carries only iSCSI traffic between the two servers.

✅ Checkpoint: SRV01 has 10.0.1.20 on Ethernet 2, and NODE1 is joined with 10.0.0.41 and 10.0.1.41.

2Build the iSCSI target on SRV01

On SRV01:

Install-WindowsFeature FS-iSCSITarget-Server -IncludeManagementTools | Out-Null
New-Item -ItemType Directory D:\iSCSI -Force | Out-Null
New-IscsiVirtualDisk -Path D:\iSCSI\Node1-Data.vhdx -SizeBytes 10GB | Out-Null
New-IscsiServerTarget -TargetName NodeTarget -InitiatorIds 'IQN:iqn.1991-05.com.microsoft:node1.saatlab.internal' | Out-Null
Add-IscsiVirtualDiskTargetMapping -TargetName NodeTarget -Path D:\iSCSI\Node1-Data.vhdx
Get-IscsiServerTarget | Select-Object TargetName, TargetIqn, @{n='Initiators';e={$_.InitiatorIds -join ', '}}

You should see something like this:

TargetName TargetIqn                                         Initiators
---------- ---------                                         ----------
NodeTarget iqn.1991-05.com.microsoft:srv01-nodetarget-target IQN:iqn.1991-05.com.microsoft:node1.saatlab.internal

The LUN is just a VHDX file on D:. Only NODE1’s IQN is allowed; Windows initiators use iqn.1991-05.com.microsoft: plus the computer’s FQDN by default.

✅ Checkpoint: NodeTarget exists, maps Node1-Data.vhdx, and allows only NODE1’s IQN.

3Connect NODE1 over two paths with MPIO

On NODE1, start the initiator, install MPIO and let it claim iSCSI disks:

Set-Service MSiSCSI -StartupType Automatic; Start-Service MSiSCSI
(Get-InitiatorPort).NodeAddress
Install-WindowsFeature Multipath-IO | Out-Null
Enable-MSDSMAutomaticClaim -BusType iSCSI
Restart-Computer

After the restart, connect through both networks:

New-IscsiTargetPortal -TargetPortalAddress 10.0.0.20 -InitiatorPortalAddress 10.0.0.41 | Out-Null
New-IscsiTargetPortal -TargetPortalAddress 10.0.1.20 -InitiatorPortalAddress 10.0.1.41 | Out-Null
$iqn = (Get-IscsiTarget).NodeAddress
Connect-IscsiTarget -NodeAddress $iqn -TargetPortalAddress 10.0.0.20 -InitiatorPortalAddress 10.0.0.41 -IsPersistent $true -IsMultipathEnabled $true | Out-Null
Connect-IscsiTarget -NodeAddress $iqn -TargetPortalAddress 10.0.1.20 -InitiatorPortalAddress 10.0.1.41 -IsPersistent $true -IsMultipathEnabled $true | Out-Null
Get-IscsiSession | Select-Object InitiatorPortalAddress, TargetNodeAddress, IsConnected
mpclaim -s -d

You should see something like this:

InitiatorPortalAddress TargetNodeAddress                                    IsConnected
---------------------- -----------------                                    -----------
10.0.0.41              iqn.1991-05.com.microsoft:srv01-nodetarget-target           True
10.0.1.41              iqn.1991-05.com.microsoft:srv01-nodetarget-target           True

For more information about a particular disk, use 'mpclaim -s -d #' where # is the MPIO disk number.

MPIO Disk    System Disk  LB Policy    DSM Name
-------------------------------------------------------------------------------
MPIO Disk0   Disk 1       RR           Microsoft DSM

Bring the disk online and format it:

Get-Disk | Where-Object BusType -eq 'iSCSI' | Select-Object Number, Size, PartitionStyle
Get-Disk -Number 1 | Initialize-Disk -PartitionStyle GPT -PassThru | New-Partition -DriveLetter S -UseMaximumSize | Format-Volume -FileSystem NTFS -NewFileSystemLabel Shared -Confirm:$false | Out-Null

Two sessions, one disk: MPIO merged the paths, with round-robin (RR) load balancing. Without MPIO, Disk 1 and Disk 2 would appear as two separate disks pointing at the same LUN, a recipe for corruption.

✅ Checkpoint: NODE1 has two connected sessions, mpclaim shows one MPIO disk, and drive S: is formatted.

4Create a mirrored Storage Spaces disk on SRV01

On SRV01:

Get-PhysicalDisk -CanPool $true | Select-Object FriendlyName, Size, MediaType
New-StoragePool -FriendlyName Pool1 -StorageSubSystemFriendlyName 'Windows Storage*' -PhysicalDisks (Get-PhysicalDisk -CanPool $true) | Out-Null
New-VirtualDisk -StoragePoolFriendlyName Pool1 -FriendlyName Mirror1 -ResiliencySettingName Mirror -NumberOfDataCopies 2 -Size 4GB -ProvisioningType Fixed |
    Initialize-Disk -PartitionStyle GPT -PassThru | New-Partition -DriveLetter F -UseMaximumSize | Format-Volume -FileSystem ReFS -NewFileSystemLabel Mirror1 -Confirm:$false | Out-Null
Get-VirtualDisk | Select-Object FriendlyName, ResiliencySettingName, NumberOfDataCopies, HealthStatus, OperationalStatus

You should see something like this:

FriendlyName            Size MediaType
------------            ---- ---------
ATA VBOX HARDDISK 4294967296 Unspecified
ATA VBOX HARDDISK 4294967296 Unspecified
ATA VBOX HARDDISK 4294967296 Unspecified

FriendlyName ResiliencySettingName NumberOfDataCopies HealthStatus OperationalStatus
------------ --------------------- ------------------ ------------ -----------------
Mirror1      Mirror                                 2 Healthy      OK

Every block written to F: is stored on two of the three disks. ReFS adds checksums, so Storage Spaces can repair a bad copy from the good one. Copy a few files to F: now; you’ll check they survive a failed disk.

✅ Checkpoint: Pool1 contains three disks and Mirror1 (F:) is Healthy with two data copies.