Home > Servers > PowerEdge and VMware > White Papers > Dell PowerEdge XR4000 Deployment in a vSAN 2.1 Configuration > OS deployment and pre-vSAN cluster configuration
Note: Dell factory shipped XR4000z server sleds and the witness sled will have a supported Dell version of VMware ESXi pre-installed.
Note: Due to the limited number of cores, memory, and storage of the XR4000 nodes, it is important to profile the workload prior to deployment to ensure the desired performance at the edge. The number of VMs on these nodes depends strictly on the type of workloads, CPU, storage, memory, and networking chosen for the site. The witness host XR4000w is a vital part of the vSAN 2-Node cluster at the edge/remote site. It stores all the metadata required in case of a failure and serves as a tiebreaker. The deployment of a witness host can be on-premises (Data Center hosting multiple sites up to 64) or at the Edge to help maintain higher availability of your data. Although it is possible to run multiple VMs on the XR4000w as witness for other sites, it is neither supported nor recommended for running any additional VMs, due to its capabilities and resource constraints (Intel Atom processor, 16GB memory and 1G Network adapter).
By default, the Dell factory-shipped XR4520x compute sled iDRAC provides the XR4000w (NPU) OS an IP address. For example, the following snapshot is from the compute node iDRAC where there is an explicit section for ‘Witness server’. This section displays the IP address set for VMware ESXi which is running on the witness sled. However, note that a valid DHCP server should be running on the end user network environment to get a valid IP applicable to your datacenter.
In some cases, servers might not show the witness OS IP address by default. If for some reason you do not see the witness sled OS IP address, you must use a serial connection to login to the witness sled. For additional details, see the section “Connecting to Witness using serial” in the XR4000w user manual.
If there is a need to re-install the OS on the compute nodes, perform the following steps for server sleds.
To redeploy the witness sled OS, see the section Recovery/Reinstall of the nano sled and server sleds.
After the installation and reboot, perform the following steps in the iDRAC remote console window.
esxcli vsan network ip add -i vmk0 -T witness
Navigate to Manage, configure your NTP settings, then start the service and make sure it syncs. This is a critical step to ensure cluster functionality and stability.