Dell VxRail Deploy common mistakes
Dell VxRail Deploy · Understand the traps and how to avoid them.
Sizing a VxRail cluster by dividing total required capacity by raw per-node disk capacity, then stating that node count as the validated design.
Candidates carry over general server sizing habits and forget that VxRail uses vSAN, so usable capacity is reduced by the storage policy (FTT/RAID) and by the vSAN overhead reserve, and vSAN's operational headroom must be preserved. They also forget that cluster sizing must satisfy both compute and storage constraints simultaneously and that node counts are constrained by VxRail model and vSAN limits.
What to do instead
Practice the two-pass method: size compute first (vCPU, vRAM, consolidation ratio, N+1 or N+2 resilience), then size storage using usable capacity after the chosen SPBM policy (for example FTT=1 RAID-1 roughly halves raw capacity), subtract the vSAN slack reserve, and confirm the resulting node count is a valid VxRail configuration for the chosen model. State both constraints and the binding one in the answer.
Treating the VxRail management stack (VxRail Manager, vCenter, and the platform services VMs) as ordinary workloads that can be placed anywhere, or assuming they run on the same hosts as the workload domain without accounting for their resource and network requirements.
Candidates memorize the deployment workflow but not the management-VM placement and resource rules, so they mis-size the management cluster, place management VMs on hosts that cannot reach required networks, or forget that management components need their own resilience treatment.
What to do instead
Learn where each management component runs in the target release, its per-VM vCPU/vRAM/disk footprint, and its network requirements. In design questions, explicitly reserve management capacity, state the resilience approach for management VMs, and verify that management and workload traffic can be separated per the design.
Producing a network design that assigns a single VLAN to all traffic types or that omits the VxRail-specific internal networks, then declaring the design complete.
Candidates focus on the obvious management and vMotion networks and forget that VxRail requires dedicated networks for vSAN, internal host management, and the VxRail Manager-to-host control path, each with its own addressing and MTU expectations. They also forget that some of these networks are configured by the deployment tool and must be pre-planned, not discovered later.
What to do instead
Build a table listing every required network (management, vMotion, vSAN, VM/appliance traffic, internal host management, VxRail Manager control, and out-of-band/iDRAC) with VLAN ID, subnet, gateway, MTU, and which component consumes it. Verify that the planned VLANs exist on the physical switches and that trunk/allowed-VLAN lists match before starting deployment.
Assuming the customer's existing top-of-rack switches and uplinks will work without verifying MTU, spanning-tree, LACP, and multicast requirements for the chosen vSAN and VxRail network profile.
Candidates treat physical switching as out of scope and skip the pre-deployment physical network validation, so they miss jumbo-frame mismatches, missing LAG configuration, or multicast requirements that only surface as deployment or vSAN health failures.
What to do instead
Work through a pre-deployment switch checklist: end-to-end MTU test (including the vSAN and vMotion VLANs), correct LAG/LACP or static port-channel on both sides, spanning-tree edge/PortFast settings on host ports, IGMP snooping and querier configuration if multicast is used, and consistent VLAN pruning on uplinks. Record the verification commands and expected results.
Skipping or misinterpreting the pre-deployment readiness checks (host discovery, iDRAC/BIOS firmware baseline, DNS forward and reverse records, NTP reachability, and credentials) and proceeding to imaging hoping errors will resolve themselves.
Candidates are eager to reach the visible deployment wizard and treat preparation as paperwork. In practice most failed deployments trace back to a PTR record that does not match, an unreachable NTP server, a firmware level outside the supported matrix, or a service account without sufficient privileges.
What to do instead
Treat the readiness checklist as a gate: confirm forward and reverse DNS for every management address and the VxRail Manager name, confirm NTP synchronization from each host, verify iDRAC reachability and credentials, and confirm the firmware baseline matches the target VxRail release. Learn to read the specific error text of each pre-check and map it to the underlying misconfiguration.
Confusing the roles of the VxRail deployment tooling layers, for example expecting the VxRail Manager plugin or the configuration wizard to perform tasks that belong to the imaging step, or assuming a failed step can simply be re-run from a later stage.
Candidates memorize menu names without understanding the sequence: discovery and validation, imaging and firmware update, configuration and cluster creation, then validation. Because they do not know which step owns which action, they misdiagnose where a failure occurred and choose a remediation that restarts the wrong phase.
What to do instead
Map the deployment workflow to its ordered phases and, for each phase, note the inputs it consumes, the artifacts it produces, and the log or UI location that reports its status. When answering a troubleshooting question, first identify the phase from the symptom, then choose the remediation appropriate to that phase (for example re-image a host rather than re-running cluster configuration).
Planning an IP address scheme without reserving the addresses the deployment consumes (VxRail Manager, per-host management, iDRAC, vSAN VMkernel, vMotion VMkernel) and without documenting which pool is static versus DHCP.
Candidates design at the subnet level and stop there, forgetting that VxRail needs a precise, non-overlapping address plan and that some addresses are assigned by the deployment tool while others must be pre-created. Address collisions and pool exhaustion are among the most common causes of a stalled deployment.
What to do instead
Produce an explicit IP plan with one row per address, its purpose, whether it is static or DHCP-reserved, and its DNS name. Reserve a contiguous block for host management and VMkernel interfaces, keep iDRAC on a separate out-of-band subnet where required, and verify no overlap with existing corporate ranges before deployment.
Assuming a newly built cluster is production-ready, without verifying vSAN health, cluster baseline compliance, and network redundancy after deployment completes.
The deployment tool reports success when configuration finishes, and candidates equate that success message with a validated environment. Post-deployment checks such as vSAN resync status, disk group health, firmware/driver baseline compliance, and redundant path verification are separate tasks that the exam tests explicitly.
What to do instead
Adopt a standard post-deployment validation sequence: confirm all hosts are connected and licensed, verify vSAN health and that no components are degraded or resyncing, check the cluster baseline and remediate non-compliance, verify redundant uplinks and failover, and confirm backups/monitoring are attached. Be able to name where each check is performed.
Troubleshooting a failed host expansion or a host in an inconsistent state by immediately removing and re-adding the host, without first checking whether the failure is a network, credential, firmware, or vSAN-level issue.
Candidates reach for the most visible destructive action because they lack a diagnostic order. Removing a host that still holds vSAN components, or re-adding it before resolving the underlying cause, can cause data re-protection churn or repeat the same failure.
What to do instead
Use a layered diagnostic order: physical and out-of-band reachability, management network and DNS, credentials and certificates, firmware baseline, then vSAN membership and component state. Only after the root cause is identified should you choose between remediation in place, maintenance-mode-based removal, or re-imaging.
Answering troubleshooting questions with generic advice such as 'check the logs' or 'contact support' instead of naming the specific log bundle, health check, or command that isolates the fault.
Candidates know the concepts but have not practiced the operational surface, so under exam pressure they fall back on vague answers that do not demonstrate the procedural knowledge the question is testing.
What to do instead
Build a personal reference of the concrete diagnostic artifacts for each failure class: the VxRail Manager log locations, the support bundle generation path, the vSAN health check names, the host client esxcli commands for network and storage verification, and the iDRAC log locations. Practice describing, in one sentence each, which artifact you would open first for a given symptom and what you expect to see.