7.3.2.3 Example Virtual Machine Specification
Using the example in the table below, the number of vSAN objects and components are calculated.
Table 12. Virtual Machine Specification
Specification | Value |
Guest OS | Windows 10 |
Clone type | Linked Clone (Composer) |
Configured Memory | 4GB |
vCPU | 2 |
System disk | 40 GB |
User data disk | None |
App Volumes AppStacks | 3 |
App Volumes Writeable Volume | 1* |
Snapshots | None |
Number of Objects | 8 |
* Only 1 writeable volume per virtual machine is possible. |
Using the example in this table, there are the following objects for the virtual machine:
• Virtual machine namespace
• Virtual swap
• OS Disk (VMDK)
• Internal disk (used by Linked Clones)
• AppStack 1 (Redo-log)
• AppStack 2 (Redo-log)
• AppStack 3 (Redo-log)
• Writeable Volume
Each App Volumes AppStack is read-only and accessible to multiple virtual machines, which is achieved by mounting them as independent non-persistent disks. This means that a single AppStack (VMDK) can be mounted on many hundreds or thousands of virtual machines, and any changes that occur while the AppStack is mounted are written to a delay called a Redo-log. While the object count above includes the AppStack, it is the Redo-log file object that will exist in the namespace for each virtual machine.
Consider the following virtual machine namespace file structure:
Figure 17. vSAN Datastore VM Namespace Example
In this example, WindowsXX03 has these objects:
• WindowsXX03 VM namespace
• WindowsXX03 VMDK
• WindowsXX03 virtual swap
• AppStack1 Redo-log
The AppStack objects are only counted once as they reside in the cloudvolumes namespace.
