VSA是为中小企业无共享存储的环境设计的，最多官方推荐3台ESXi主机构成，减少部署成本，但是官方报价7999美金，不免是一种遗憾！！但是技术依然是有意义的，特别是在中国这个特殊的IT版权环境下
The following illustration depicts failover in a VSA cluster with 3 members.
The total capacity of a VSA cluster is the sum of the capacities of all VSA datastores. A VSA cluster can have 2 or 3 VSA datastores.
The VSA datastore capacity is calculated after ESXi installation takes hard disk space for root, swap, and dumppartitions and after VSA installation reserves 20GB or more for local virtual machine swap files. Because of this, the following calculations are approximate.
In a VSA cluster with 4, 6, or 8 hard disks per ESXi host and a RAID10 configuration, the capacity of the VSA cluster depends on two variables.
| ■ | Total hard disk capacity per ESXi host |
| ■ | Number of ESXi hosts in the VSA cluster (2 or 3) |
The capacity of a VSA datastore equals the total hard disk capacity of the ESXi host divided by 4. This is due to the RAID10 configuration on each ESXi host and the mirroring of VSA volumes between VSA cluster members.
Determine the VSA datastore capacity by using the following formula.
VSA datastore capacity = hard disk capacity of an ESXi host / 4
Where
hard disk capacity of an ESXi host = the total capacity of the hard disks that are installed internally on the ESXi host
If you create a VSA cluster with hosts that have different total hard disk capacities, the lowest hard disk capacity from all ESXi hosts becomes the basis for calculating the capacity of every VSA datastore. In such a situation, some of the total hard disk capacity remains unused.
Hard disk capacity per ESXi host = 8TB
Total hard disk capacity of all ESXi hosts = 24TB
VSA datastore capacity = 8TB / 4 = 2TB
Total VSA cluster capacity = 2TB * 3 hosts = 6TB
Hard disk capacity of ESXi host 1 = 6TB
Hard disk capacity of ESXi host 2 = 8TB
Hard disk capacity of ESXi host 3 = 8TB
Total hard disk capacity = 22TB
VSA datastore capacity = 6TB / 4 = 1.5TB
