For full availability, VMware recommends that customers should be running at 50% of resource consumption across the vSAN Stretched Cluster. If a complete site fails, all the virtual machines can be run on the surviving site.
VMware understands that some customers will want to run levels of resource utilization higher than 50%. While it is possible to run at higher utilization in each site, customers should understand that if a failure occurs, not all virtual machines will be restarted on the surviving site.
Table 3. Stretched Cluster Capacity
Across Sites Only | 1 | Mirroring | 0 | 100% of VM | 100% of VM | 200% of VM |
Mirroring (RAID 1 Single Failure) | 1 | Mirroring | 1 | 200% of VM | 200% of VM | 400% of VM |
Mirroring (RAID 1 Double Failure) | 1 | Mirroring | 2 | 300% of VM | 300% of VM | 600% of VM |
Mirroring (RAID 1 Triple Failure) | 1 | Mirroring | 3 | 400% of VM | 400% of VM | 800% of VM |
Erasure Coding (RAID5/Single Failure) | 1 | Erasure Coding | 1 | 133% of VM | 133% of VM | 266% of VM |
Erasure Coding (RAID6/Double Failure) | 1 | Erasure Coding | 2 | 150% of VM | 150% of VM | 300% of VM |
