Configuring vSAN

Ensure that the minimum compute requirements (detailed in the following table) are met before configuring the vSAN datastore.

All components must be certified as compatible with VMware to guarantee performance. A sizing tool is available (vSAN ReadyNode Sizer) to assist.

Prerequisites for vSAN Cluster

Host (servers): Three or more (2+1 in a 2-node or stretched cluster).
CPU: vSAN operational overhead uses approximately 10% of the available CPU.
Memory: See vSAN ReadyNode Sizer.
Storage Devices: One or more cache disk with one or more capacity disk or host, depending on fault tolerance requirements.

Table 1. vSAN Networking Requirements
Networking Component	Requirement
Host Bandwidth	Each host must have minimum bandwidth dedicated to vSAN. Dedicated 1 Gbps for hybrid configurations. Dedicated or shared 10 Gbps for all-flash configurations. For information about networking considerations in vSAN, see Designing the vSAN Network.
Connection between hosts	Each host in the vSAN cluster, irrespective of whether it contributes capacity, must have a VMkernel network adapter for vSAN traffic. See Set Up a VMkernel Network for vSAN.
Host network	All hosts in a vSAN cluster must be connected to a vSAN Layer 2 or Layer 3 network.
IPv4 and IPv6 support	The vSAN network supports both IPv4 and IPv6.
Network latency	Maximum of 1 ms RTT for standard (non-stretched) vSAN clusters between all hosts in the cluster. Maximum of 5 ms RTT between the two main sites for stretched clusters. Maximum of 500 ms RTT from a main site to the vSAN witness host.

Figure 1. Sample vSAN Deployment Block Diagram

Before you begin creating a vSphere cluster, review the features that can be used for non-real-time workloads:

vSphere Distributed Resource Scheduler (DRS) – Enabled
- DRS is desirable for vSAN because it provides initial placement assistance of VMs and load balance the environment when there is an imbalance, and migrates virtual machines to their correct site based on the VM or host affinity rules.
- To configure a vPAC-based application, given its real-time characteristics, the VMs must be pinned to a specific host and disallowed from migrating during use. Thus, vPAC VMs must not be used on vSAN with DRS enabled.
vSphere High Availability (HA) – Enabled
- Host Monitoring - Enabled
- Failure conditions and responses:
  - Host failure – Restart VMs
    Restart VMs using VM restart priority ordering.
  - Proactive HA – Enabled
    Response for host degradation, before complete failure.
  - Host Isolation – Disabled
    VMs on isolated hosts remain powered on.
  - Datastore with Permanent Device Loss – Power off and restart VMs
    Datastore protection enabled. Always attempt to restart VMs.
  - Datastore with All Paths Down – Power off and restart VMs
    Datastore protection enabled. Ensure resources are available before restarting VMs.
  - Guest not heart beating – Reset VMs
    VM monitoring enabled. VMs are reset.
vSAN Services – Enabled
- Deduplication and compression – Enabled
  Reduces the data stored on the physical disks. Deduplication and compression only works for all-flash disk groups.
- Encryption – Disabled
  Data-at-rest encryption.
- Performance Service – Enabled
  The performance service collects and analyzes statistics, and displays the data in a graphical format.
- vSAN iSCSI Target Service – Disabled
  Allows the exposure of vSAN storage capacity to hosts outside of this cluster.
- File Service – Disabled
  Allows a vSphere admin to provision a file share from their vSAN cluster. The file share can be accessed using NFS.

vSAN setup can commence after the appropriate hardware is in place for a desired cluster configuration, ESXi is running on all hosts, and vCenter is running in an accessible location.

In vCenter, a cluster (of hosts) must first be created, if it does not already exist. To create a cluster, right-click the data center and click New Cluster.

Figure 2. New Cluster
Select the appropriate options for your environment and complete the cluster initialization.
Go to the Configure menu of the new cluster that you created.

Figure 3. Create Cluster

Figure 4. Configure Cluster
For each host, add the host IP address or FQDN with the login credentials for ESXi.
Note:
- When setting up a 2-node cluster, include only the primary and secondary hosts. The witness node is set up separately.
- When using the Quickstart method to configure vSAN, three distributed switches are set up. If you require more switches, add them manually later.
Figure 5. Add Hosts to Cluster
Now, configure vSAN for two-clustered hosts.

Figure 6. Configure vSAN

Figure 7. vSAN Stretched Cluster Option

A two-node vSAN cluster refers to a configuration where both data nodes are at the same site and are connected by a switch or back-to-back. This choice, therefore, does not include a fault domain configuration step.

A stretched cluster can have more than two data nodes and assumes that nodes are physically located at separate sites, and therefore preferred, and secondary node assignments must be made.

Both the preferred and secondary nodes are ideally still equivalent machines, but the preferred is assigned as the primary for vSAN purposes (unless communication to it is lost to both the witness and secondary hosts).

The data path between the two nodes in either setup must be able to achieve less than 5 ms round trip time for data latency (typically achievable with 10 Gbps or higher network links).

The vSAN configurator guides the selection of cache and capacity disks. The cache disks or capacity tiers (which must be flash or SSD type) must have high write endurance and can be of small capacity. The capacity disks or capacity tiers must have at least one disk, preferably of high capacity.

Fault tolerance considerations must be made and edited as required based on the organization. The VM storage policies can be viewed or edited by navigating to vSphere Client’s Policies and Profiles menu.

Figure 8. vSAN Stretched Cluster Fault Domain Selection

The vSAN default storage policy (where failures to tolerate are set to 1 – RAID 1 Mirroring by default) can be changed here.

The number of failures to tolerate sets a requirement of disks to be # of failures + 1 replica to remain available for fail over.

After the configuration is finished, you can use the new vSAN datastore for VM deployment. Reviewing the Cluster\Configure\Quickstart menu after configuration can help to resolve any issues with the vSAN architecture.

The Configure hosts area displays the individual checks that are being performed automatically and are links into the separate areas of analysis (for example, network, physical disk).