3 Node vSAN with All-Flash

[Bilal233]

Hi Expert,

i have a question regarding vSAN ALL-Flash , How many Nodes required for vSAN All-Flash( 3 or 4 ).

Can i use 3 Nodes vSAN Cluster with All-Flash or not ,As i know that 4 Nodes are a minimum requirement for All-Flash that support Raid5/6 , if All-Flash 3 Nodes is with Raid1 , don't want to use Raid5/6 , is it OK or not  or i must have a 4 Nodes for All-Flash  vSAN .

please also share the link for All-Flash and Hybrid vSAN minimum Hosts Required .

Thanks

[CyberNils]

Yes, you can use 3 nodes, but it is recommended to have 4 so that you can take down one node for maintenance and still be compliant.

Check this out for details on how many nodes you need for the different configurations: https://core.vmware.com/resource/vmware-vsan-design-guide#sec6-sub5

[Bilal233]

Thanks Nils for clarification .

one more question , does Raid5 option will be available or not on 3Node vSAN All-Flash.

[TheBobkin]

@Bilal233, So, actually the minimum size cluster (All-Flash or Hybrid) is 2 data-nodes + a Witness (basically nested-ESXi running as a VM somewhere outside of the cluster) or 3 physical servers. In a 3-node cluster only RAID1 or RAID0 can be used as the FTM (Fault Tolerance Method) as RAID1 requires 3 nodes for component placement (data-replica+data-replica+witness component) whereas RAID5 requires at least 4 nodes for component placement (with all 4 components being a combination of data and parity metadata), so no you cannot make RAID5 Objects in a 3-node cluster (whether it is All-Flash or not).

Note also that using RAID5/6 FTM requires vSAN Advanced or higher licensing level (whereas All-Flash only requires vSAN Standard level) which would increase the cost of the cluster:
https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/products/vsan/vmware-vsan-licensin...

[CyberNils]