“Extra-large“ OVA file size option for shared witness deployment introduced with vSAN 7 Update 2 release

June 03, 2021

 

The shared witness appliance feature in vSAN 7 U1 brought the opportunity to significantly reduce the upfront cost of 2 Node cluster deployments by sharing a single witness host or appliance with a maximum of 64 2-node clusters.  This new option is most beneficial for organizations that have multiple site offices or retail branches. For example, a topology with 30 remote sites would have previously needed 240 GB of RAM at the central site for the witness host appliance, while using the shared witness model would require 16 GB.

Each shared witness can be deployed as a host or as a witness appliance by deploying an OVA template. A new “Extra-large“ OVA file size option has been included in vSAN 7 Update 2 to accommodate the shared witness appliance's increased number of components. Each 2-node cluster can store a maximum of 1000 witness components.

The table below will help you select the right OVA file size for your deployment configuration. The table contains the new sizing options for a shared witness appliance in comparison to the ones for a dedicated witness:

Dedicated witness Shared witness

•    Tiny - Supports up to 10 VMs/750 Witness Components 

o    Compute - 2 vCPUs
o    Memory - 8GB vRAM

•    Tiny - Supports up to 10 VMs/750 Witness Components 

o    Compute - 1 vCPUs
o    Memory - 8GB vRAM

•    Medium - Supports up to 500 VMs/21,000 Witness Components

o    Compute - 2 vCPUs
o    Memory - 16GB vRAM

•    Medium - Supports up to 500 VMs/21,000 Components 

o    Up to 21 clusters 2-node clusters 
o    Compute - 2 vCPUs
o    Memory - 16GB vRAM

•    Large - Supports over 500 VMs/45,000 Witness Components 

o    Compute: 2 vCPUs
o    Memory - 32 GB vRAM

 

•    Large - Supports over 500 VMs/ 24,000 Components 

o    Up to 24 clusters 2-node clusters 
o    Compute: 2 vCPUs
o    Memory - 32 GB vRAM

Not available

•    Extra-large - Supports over 500 VMs/ 64,000 Components 

o    Up to 64 clusters 2-node clusters 
o    Compute: 6 vCPUs
o    Memory - 32 GB vRAM

Note: These estimates are based on standard VM configurations. The number of components that make up a VM can vary, depending on the number of virtual disks, policy settings, snapshot requirements, and so on. 

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Teodora Hristov

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Teodora Todorova Hristov works as a vSAN Technical Marketing content creator in the CPBU at VMware. She is primarily focused on vSAN.