Key concepts

Earlier, we touched upon disk groups and network requirements. Let's revisit them and add more context to how they impact the VSAN cluster.

Disk groups

Disk groups, as we defined earlier, are containers of a set ratio of SSDs to HDDs. Each disk group should have one SSD and a minimum of one HDD. The number of HDDs can be increased up to a maximum of seven per disk group. The aggregate of these disk groups from all the hosts in the cluster that contribute storage form a single large VSAN datastore. The composition of the disk group in particular plays a very important role in the performance outcome in a VSAN cluster.

SSDs contribute to performance and HDDs contribute to capacity. A higher ratio of SSD to HDD improves the performance, while the typical requirement is to have at least 10 percent SSDs. The role of SSDs is to accelerate the I/O throughput. The capacity of SSDs is split into two, 70 percent for read caching and 30 percent for write buffering.

Hence, if there is...