Part 1: Intro and Architecture
Part 2: Prep & Configuration
Part 3: Performance & Troubleshooting (you are here)
Make sure to check out my series on RDS in Server 2016 for more detailed information on designing and deploying RDSH or RDVH.

Performance

This section will give an idea of disk activity and performance given this specific configuration as it relates to S2D and RDS.
Here is the 3-way mirror in action during the collection provisioning activity, 3 data copies, 1 per host, all hosts are active, as expected:

Real-time disk and RDMA stats during collection provisioning:

RDS provisioning isn’t the speediest solution in the world by default as it creates VMs one by one. But it’s fairly predictable at 1 VM per minute, so plan accordingly.

Optionally, you can adjust the concurrency level to adjust the number of VMs RDS can create in parallel by using the Set-RDVirtualDesktopConcurrency CMDlet. Server 2012R2 supported a max of 20 concurrent operations but make sure the infrastructure can handle whatever you set here.

Set-RDVirtualDesktopConcurrency –ConnectionBroker “RDCB name” –ConcurrencyFactor 20

To illustrate the capacity impact of 3-way mirroring, take my lab configuration which provides my 3-node cluster with 14TB of total capacity, each node contributing 4.6TB. I have 3 volumes fixed provisioned totaling 4TB with just under 2TB remaining. The math here is that of my raw capacity, 30% is usable, as expected. This equation gets better at larger scales, starting with 4 nodes, so keep this in mind when building your deployment.

Here is the disk performance view from one of the Win10 VMs within the pool (VDI-23) running Crystal DiskMark, which runs Diskspd commands behind the scenes. Read IOPS are respectable at an observed max of 25K during the sequential test.

Write IOPS are also respectable at a max observed of nearly 18K during the Sequential test.

Writing to the same volume, running the same benchmark but from the host itself, I saw some wildly differing results. Similar bandwidth numbers but poorer showing on most tests for some reason. One run yielded some staggering numbers on the random 4K tests which I was unable to reproduce reliably.
Running Diskspd tells a slightly different story with more real-world inputs specific to VDI: write intensive. Here given the punishing workload, we see impressive disk performance numbers and almost 0 latency. The following results were generated from a run generating a 500MB file, 4K blocks weighted at 70% random writes using 4 threads with cache enabled.

Diskspd.exe -b4k -d60 -L -o2 -t4 -r -w70 -c500M c:\ClusterStorage\Volume1\RDSH\io.dat

Just for comparison, here is another run with cache disabled. As expected, not so impressive.

Troubleshooting

Here are a few things to watch out for along the way.
When deploying your desktop collection, if you get an error about a node not having a virtual switch configured:

One possible cause is that the default SETSwitch was not configured for RDMA on that particular host. Confirm and then enable per the steps above using Enable-NetAdapterRDMA.


On the topic of VM creation within the cluster, here is something kooky to watch out for. If working on one of your cluster nodes locally and you try to add a new VM to be hosted on a different node, you may have trouble. When you get to the OS install portion where the UI offers to attach an ISO to boot from. If you point to an ISO sitting on a network share, you may get the following error: Failing to add the DVD device due to lack of permissions to open attachment.

You will also be denied if you try to access any of the local paths such as desktop or downloads.
The reason for this is that the dialog is using the remote browser for file access on the server you are creating the VM. Counter-intuitive perhaps but the work around is to either log into the host where the VM is to be created directly or copy your ISO local to that host. 

Watch this space, more to come…

Part 1: Intro and Architecture
Part 2: Prep & Configuration
Part 3: Performance & Troubleshooting (you are here)

Resources

S2D in Server 2016
S2D Overview
Working with volumes in S2D
Cache in S2D

Part 1: Intro and Architecture
Part 2: Prep & Configuration (you are here)
Part 3: Performance & Troubleshooting
Make sure to check out my series on RDS in Server 2016 for more detailed information on designing and deploying RDSH or RDVH.

Prep

The number 1 rule of clustering with Microsoft is homogeneity. All nodes within a cluster must have identical hardware and patch levels. This is very important. The first step is to check all disks installed to participate in the storage pool, bring all online and initialize. This can be done via PoSH or UI.

Once initialized, confirm that all disks can pool:

Get-PhysicalDisk -CanPool $true | sort model

Install Hyper-V and Failover Clustering on all nodes:

Install-WindowsFeature -name Hyper-V, Failover-Clustering -IncludeManagementTools -ComputerName InsertName -Restart

Run cluster validation, note this command does not exist until the Failover Clustering feature has been installed. Replace portions in red with your custom inputs. Hardware configuration and patch level should be identical between nodes or you will be warned in this report.

Test-Cluster -Node node1, node2, etc -include "Storage Spaces Direct", Inventory, Network, "System Configuration"

The report will be stored in c:\users\<username>\AppData\Local\Temp

Networking & Cluster Configuration

We'll be running the new Switch Embedded Team (SET) vSwitch feature, new for Hyper-V in Server 2016.

Repeat the following steps on all nodes in your cluster. First, I recommend renaming the interfaces you plan to use for S2D to something easy and meaningful. I'm running Mellanox cards so called mine Mell1 and Mell2. There should be no NIC teaming applied at this point!


Configure the QoS policy, first enable the datacenter bridging (DCB) feature which will allow us to prioritize certain services the traverse the Ethernet.

Install-WindowsFeature -Name Data-Center-Bridging

Create a new policy for SMB Direct with a priority value of 3 which marks this service as “critical” per the 802.1p standard:

New-NetQosPolicy "SMBDirect" -NetDirectPortMatchCondition 445 -PriorityValue8021Action 3

Allocate at least 30% of the available bandwidth to SMB for the S2D solution:

New-NetQosTrafficClass "SMBDirect" -Priority 3 -BandwidthPercentage 30 -Algorithm ETS

Create the SET switch using the adapter names you specified previously. Items in red should match your choices or naming standards. Note that this SETSwitch is ultimately a vNIC and can receive an IP address itself:

New-VMSwitch -Name SETSwitch -NetAdapterName "Mell1","Mell2" -EnableEmbeddedTeaming $true

Add host vNICs to the SET switch you just created, these will be used by the management OS. Items in red should match your choices or naming standards. Assign static IPs to these vNICs as required as these interfaces are where RDMA will be enabled.

Add-VMNetworkAdapter –SwitchName SETSwitch –name SMB_1 –managementOS
Add-VMNetworkAdapter –SwitchName SETSwitch –name SMB_2 –managementOS

Once created, the new virtual interface will be visible in the network adapter list by running get-netadapter.

Optional: Configure VLANs for the new vNICs which can be the same or different but IP them uniquely. If you don’t intend to tag VLANs in your cluster or have a flat network with one subnet, skip this step.

Set-VMNetworkAdapterVLAN –VMNetworkAdapterName “SMB_1” –VlanId 00 –Access –ManagementOS
Set-VMNetworkAdapterVLAN –VMNetworkAdapterName “SMB_2” –VlanId 00 –Access –ManagementOS

Verify your VLANs and vNICs are correct. Notice mine are all untagged since this demo is in a flat network.

Get-VMNetworkAdapterVlan –ManagementOS

Restart each vNIC to activate the VLAN assignment.

Restart-NetAdapter “vEthernet (SMB_1)”
Restart-NetAdapter “vEthernet (SMB_2)”

Enable RDMA on each vNIC.

Enable-NetAdapterRDMA “vEthernet (SMB_1)”, “vEthernet (SMB_2)”

Next each vNIC should be tied directly to a preferential physical interface within the SET switch. In this example we have 2 vNICs and 2 physical NICs for a 1:1 mapping. Important to note: Although this operation essentially designates a vNIC assignment to a preferential pNIC, should the assigned pNIC fail, the SET switch will still load balance vNIC traffic across the surviving pNICs. It may not be immediately obvious that this is the resulting and expected behavior.

Set-VMNetworkAdapterTeamMapping -VMNetworkAdapterName "SMB_1" -ManagementOS –PhysicalNetAdapterName “Mell1”
Set-VMNetworkAdapterTeamMapping -VMNetworkAdapterName "SMB_2" -ManagementOS –PhysicalNetAdapterName “Mell2”

To quickly prove this, I have my vNIC “SMB_1” preferentially tied to the pNIC “Mell1”. SMB_1 has the IP address 10.50.88.82

Notice that even though I have manually disabled Mell1, the IP still responds to a ping from another host as SMB_1’s traffic is temporarily traversing Mell2:

Verify the RDMA capabilities of the new vNICs and associated physical interfaces. RDMA Capable should read true.

Get-SMBClientNetworkInterface

Build the cluster with a dedicated IP and slash subnet mask. This command will default to /24 but still might fail unless explicitly specified.

New-Cluster -name "Cluster Name" -Node Node1, Node2, etc -StaticAddress 0.0.0.0/24

Checking the report output stored in c:\windows\cluster\reports\, it flagged not having a suitable disk witness. This will auto-resolve later once the cluster is up.


The cluster will come up with no disks claimed and if there is any prior formatting, they must first be wiped and prepared. In PowerShell ISE, run the following script, enter your cluster name in the red text.

icm (Get-Cluster -Name S2DCluster | Get-ClusterNode) {
Update-StorageProviderCache


Get-StoragePool | ? IsPrimordial -eq $false | Set-StoragePool -IsReadOnly:$false -ErrorAction SilentlyContinue


Get-StoragePool | ? IsPrimordial -eq $false | Get-VirtualDisk | Remove-VirtualDisk -Confirm:$false -ErrorAction SilentlyContinue


Get-StoragePool | ? IsPrimordial -eq $false | Remove-StoragePool -Confirm:$false -ErrorAction SilentlyContinue


Get-PhysicalDisk | Reset-PhysicalDisk -ErrorAction SilentlyContinue


Get-Disk | ? Number -ne $null | ? IsBoot -ne $true | ? IsSystem -ne $true | ? PartitionStyle -ne RAW | % {


$_ | Set-Disk -isoffline:$false


$_ | Set-Disk -isreadonly:$false


$_ | Clear-Disk -RemoveData -RemoveOEM -Confirm:$false


$_ | Set-Disk -isreadonly:$true


$_ | Set-Disk -isoffline:$true


}


Get-Disk |? Number -ne $null |? IsBoot -ne $true |? IsSystem -ne $true |? PartitionStyle -eq RAW | Group -NoElement -Property FriendlyName


} | Sort -Property PsComputerName,Count

Once successfully completed, you will see an output with all nodes and all disk types accounted for.

Finally, it’s time to enable S2D. Run the following command and select “yes to all” when prompted. Make sure to use your cluster name in red.

Enable-ClusterStorageSpacesDirect –CimSession S2DCluster

Storage Configuration

Once S2D is successfully enabled, there will be a new storage pool created and visible within Failover Cluster Manager. The next step is to create volumes within this pool. S2D will make some resiliency choices for you depending on how many nodes are in your cluster. 2 nodes = 2-way mirroring, 3 nodes = 3-way mirroring, if you have 4 or more nodes you can specify mirror or parity. When using a hybrid configuration of 2 disk types (HDD and SSD), the volumes reside within the HDDs as the SSDs simply provide caching for reads and writes. In an all-flash configuration only the writes are cached. Cache drive bindings are automatic and will adjust based on the number of each disk type in place. In my case, I have 4 SSDs + 5 HDDs per host. This will net a 1:1 cache:capacity map for 3 pairs of disks and a 1:2 ratio for the last 3. Microsoft’s recommendation is to make the number of cache drives a multiple of the number of capacity drives, for simple symmetry. If a host experiences a cache drive failure, the cache to capacity mapping will readjust to heal. This is why a minimum of 2 cache drives per host are recommended.

Volumes can be created using PowerShell or Failover Cluster Manager by selecting the “new disk” option. This one simple PowerShell command does three things: creates the virtual disk, places a new volume on it and makes it a cluster shared volume. For PowerShell the syntax is as follows:

New-Volume –FriendlyName “Volume Name” –FileSystem CSVFS_ReFS –StoragePoolFriendlyName S2D* –size xTB

CSVFS_ReFS is recommended but CSVFS_NTFS may also be used. Once created these disks will be visible under the Disks selection within Failover Cluster Manager. Disk creation within the GUI is a much longer process but gives meaningful information along the way, such as showing that these disks are created using the capacity media (HDD) and that the 3-server default 3-way mirror is being used.
The UI also shows us the remaining pool capacity and that storage tiering is enabled.

Once the virtual disk is created, next we need to create a volume within using another wizard.  Select the vDisk created in the last step:

Storage tiering dictates that the volume size must match the size of the vDisk:

Skip the assignment of a drive letter, assign a label if you desire, confirm and create.

The final step is to add this new disk to a Cluster Shared Volume via Failover Cluster Manager. You’ll notice that the owner node will be automatically assigned:

Repeat this process to create as many volumes as required.

RDS Deployment

Install the RDS roles and features required and build a collection. See this post for more information on RDS installation and configuration. There is nothing terribly special that changes this process for a S2D cluster. As far as RDS is concerned, this is an ordinary Failover Cluster with Cluster Shared Volumes. The fact that RDS is running on S2D and “HCI” is truly inconsequential.
As long as the RDVH or RDSH roles are properly installed and enabled within the RDS deployment, the RDCB will be able to deploy and broker connections to them. One of the most important configuration items is ensuring that all servers, virtual and physical, that participate in your RDS deployment, are listed in the Servers tab. RDS is reliant on Server Manager and Server Manager has to know who the players are. This is how you tell it.


To use the S2D volumes for RDS, point your VM deployments at the proper CSVs within the C:\ClusterStorage paths. When building your collection, make sure to have the target folder already created within the CSV or collection creation will fail. Per the example below, the folder “Pooled1” needed to be manually created prior to collection creation.
During provisioning, you can select a specific balance of VMs to be deployed the RDVH-enabled hosts you select, as can be seen below.

RDS is cluster aware in that the VMs it creates can be created as HA within the cluster and the RD Connection Broker (RDCB) remains aware as to which host is running which VMs should they move. In the event of a failure, VMs will be moved to a surviving host by the cluster service and the RDCB will keep track.
Part 1: Intro and Architecture
Part 2: Prep & Configuration (you are here)
Part 3: Performance & Troubleshooting

Resources

S2D in Server 2016
S2D Overview
Working with volumes in S2D
Cache in S2D

Part 1: Intro and Architecture (you are here)
Part 2: Prep & Configuration
Part 3: Performance & Troubleshooting
Make sure to check out my series on RDS in Server 2016 for more detailed information on designing and deploying RDSH or RDVH.


For Microsoft purists looking to deploy VDI or another workload on the native Microsoft stack, this is the solution for you!  Storage Spaces Direct (S2D) is Microsoft’s new kernel-mode software-defined-storage model exclusive to Server 2016. In the last incarnation of Storage Spaces on Server 2012R2, JBODs were required with SAS cables running to each participating node that could then host SMB namespaces. No longer! Server 2016 Datacenter Edition, local disks and Ethernet (10Gb + RDMA recommended) are all you need now. The setup is executed almost exclusively in PowerShell which can be scripted, of course. Microsoft has positioned their first true HCI stack targeting the smaller side of SMB with a 16 node maximum scale. The S2D architecture runs natively on a minimum of 2 nodes configured in a Failover Cluster with 2-way mirroring.
NVMe, SSD or HDDs installed in each host are contributed to a 2-tier shared storage architecture using clustered mirror or parity resiliency models. S2D supports hybrid or all-flash models with usable disk capacity calculated using only the capacity tier. SSD or NVMe can be used for caching and SSD or HDD can be used for capacity. Or a mix of all three can be used with NVMe used for cache, SSD and HDD providing capacity. Each disk tier is extensible and can be modified up or down at any time. Dynamic cache bindings ensure that the proper ratio of cache:capacity disks remain consistent for any configuration regardless of whether cache or capacity disks are added or removed. The same is true in the case of drive failure in which case S2D self heals to ensure a proper balance. Similar to VMware VSAN, the storage architecture changes a bit between hybrid or all-flash. In the S2D hybrid model, the cache tier is used for both writes and reads. When the all-flash model is in play, the cache tier is used only for writes. Cluster Shared Volumes are created within the S2D storage pool and shared across all nodes in the cluster. Consumed capacity in the cluster is determined by provisioned volume sizes, not actual storage usage within a given volume.
A new Switch Embedded Teaming (SET) model brings NIC teaming integration to Hyper-V in a way that provides easy pNIC service protection and vNIC scale out for distributed management architectures. By contrast, in 2012R2 the teaming mechanism exists at the Windows OS layer with a few load balancing modes included. For Hyper-V in 2016 SET is the model you want to use. Important to note that this should not be combined with any other NIC teaming option, you need to use one or the other. vNICs are created to connect VMs to the SET switch or used by the Management OS for clustering or other services. If you want to use different VLANs for specific services, a vNIC per VLAN will be required. At a minimum, you will want three vNICs, one for mgmt and two for storage IO. Things like CSV, cluster heartbeating and Live Migration can easily make use of the RDMA/ SMB vNICs.
NTFS is available but ReFS is the recommended file system for most implementations which currently doesn’t support deduplication. Storage capacity efficiency is directly related to the resiliency model you choose to implement for your volumes. Mirroring does as it suggests by creating 2 or 3 copies of data on discrete hosts. Parity, also known as Erasure Coding, is similar to a RAID model which uses less storage for resiliency but at the cost of disk performance. New to Server 2016 is a mixed parity mode that allows a volume to exist as part mirror and part parity. Writes would first go to the mirror portion then later be de-staged to the parity portion. A desired level of fault tolerance will affect the minimum number of nodes required per a given configuration, as outlined in the table below.

Resiliency	Fault Tolerance	Storage Efficiency	Minimum # hosts
2-way mirror	1	50%	2
3-way mirror	2	33%	3
Dual parity	2	50-80%	4
Mixed	2	33-80%	4

Much more information on S2D resiliency and examples here. As a workload, RDS layers on top of S2D as it would with any other Failover Cluster configuration. Check out my previous series for a deeper dive into the native RDS architecture.

Lab Environment
For this exercise I’m running a 3-node cluster on Dell R630’s with the following specs per node:

• Dual E5-2698v4
• 256GB RAM
• HBA330
• 4 x 400GB SAS SSD
• 5 x 1TB SAS HDD
• Dual Mellanox ConnectX-3 NICs RDMA Over Converged Ethernet (ROCE)
• Windows 2016 Datacenter (1607)

The basic high-level architecture of this deployment:



Part 1: Intro and Architecture (you are here)
Part 2: Prep & Configuration
Part 3: Performance & Troubleshooting

Resources

S2D in Server 2016
S2D Overview
Working with volumes in S2D
Cache in S2D