VMware vSAN Interview Questions and Answers

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VMware vSAN is an enterprise-class, storage virtualization software that, when combined with vSphere, allows you to manage to compute and storage with a single platform. With vSAN, you can reduce the cost and complexity of traditional storage and take the easiest path to hyper-converged infrastructure and hybrid cloud.

In this blog we will discuss some basic of VMware vSAN interview Questions and Answers. We hope you find this helpful.

  1. What is the uses of vSAN in VMware and advantages?

vSAN provides better resilience and management on storage end. Other use cases:

  • vSAN Mixed Workload with HCI
  • vSAN Remote Office Deployment
  • vSAN For Cluster workload
  • vSAN For Disaster Recovery Plan
  • vSAN accelerates operations and lowers costs
  • vSAN is the only vSphere-native storage virtualization software
  • Operationally Simple

2. What are the vSAN Maintenance mode options available?

Before you shut down, reboot, or disconnect a host that is a member of a vSAN cluster, you must place the host in maintenance mode.

  • Ensure accessibility: This is the default option. When you power off or remove the host from the cluster, vSAN ensures that all accessible virtual machines on this host remain accessible.
  • Full data migration: vSAN evacuates all data to other hosts in the cluster, maintains or fixes availability compliance for the affected components, and protects data when sufficient resources exist in the cluster
  • No data migration: vSAN does not evacuate any data from this host. If you power off or remove the host from the cluster, some virtual machines might become inaccessible.

3. What is the basic requirements for the vSAN?

Here is the basic requirements list.

  • Min one cache(SSD) and one HDD for object storage.
  • One SAS or SATA host bus adapter (HBA).
  • All capacity devices, drivers, and firmware versions in your vSAN configuration must be certified and verified from the VMware site.
  • Min of three hosts 6.5 version or above
  • Min. 1GB or 10GB NIC.
  • Each host must configure a VMKernal network adapter for vSAN traffic.
  • IPv4 or IPv6

4. What are the limitation of vSAN?

  1. vSAN does not support hosts participating in multiple vSAN clusters.
  2. It does not support vSphere DPM and Storage I/O Control.
  3. vSAN does not support SCSI reservations.
  4. It does not support RDM, VMFS, diagnostic partition, and other device access features.

5. Does vSAN use any external storage array?

vSAN doesn’t use any external storage arrays. It uses server-based disk drives and flash devices to create its own shared pool of storage.

6. Which storage protocol does vSAN supports?

vSAN only communicates with vSphere virtual machines, It does not require for a standard storage protocol such as iSCSI or NFS.

7. Can vSAN support any server, disk, flash, IO controller, etc.?

Nope! it should match with VMware vSAN compatibility matrix guide. You can check it here.

8. Why vSAN is fast and reliable?

  • vSAN is fully integrated into the vSphere kernel which makes it faster.
  • It does not use any external storage controller.
  • Optimized IO and less resource usage.
  • Advance software engineering behind vSAN.

9. Can we share vSAN storage across multiple clusters?

Nope! It does not support storage service at multiple clusters. A single vSAN datastore can be used for a single cluster.

10. What is Storage Policy-Based Management (SPBM)?

Storage Policy-Based Management(SPBM) is the main feature of vSAN. This makes a big difference from the traditional storage model. When you enable vSAN in the virtual environment, it automatically assigns storage policy automatically to manage the performance and availability of storage.

It ensures that the virtual machines deployed to vSAN datastores are assigned at least one virtual machine storage policy. If you want to apply a custom policy, you can also configure it to the virtual machine.

11. Tell us about different configuration options for VSAN?

There are two configuration options available for vSAN:

  • Hybrid: It uses both SSD and HDD. SSD is used for flash cache and HDD is used for storing virtual machine data.
  • All-Flash: It uses flash for both caching and for storage purpose.

12. What is the maximum disk groups and magnetic disks(HDD) are allowed in a single disk group?

In a vSAN Cluster, there can be maximum of 5 disk groups are allowed on an ESXi host which is a part of a vSAN cluster and a maximum of 7 magnetic(HDD) and 1 SSD per disk group is allowed.

13. What is vSAN storage policies?

vSAN storage policies define storage requirements for virtual machines. These policies determine how the virtual machine storage objects are provisioned and allocated within the datastore to guarantee the required level of service.

When you enable vSAN on a host cluster, a single vSAN datastore is created and a default storage policy is assigned to the datastore.

14. Can we Change the Default Storage Policy for vSAN Datastores?

Yes. Just follow below steps:

  • Navigate to the vSAN datastore.
  • Click Configure.
  • Under General, click the Default Storage Policy Edit button, and select the storage policy that you want to assign as the default policy to the vSAN datastore.
  • Select a policy and click OK.

15. What is Fault Domains in vSAN Clusters?

Fault domains enable you to protect against rack or chassis failure if your vSAN cluster spans across multiple racks or blade server chassis. A fault domain consists of one or more vSAN hosts grouped according to their physical location in the data center.

The Primary level of failures to tolerate policy for the cluster depends on the number of failures a virtual machine is provisioned to tolerate. When a virtual machine is configured with the Primary level of failures to tolerate set to 1 (PFTT=1), vSAN can tolerate a single failure of any kind and of any component in a fault domain, including the failure of an entire rack.

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