vFoglight Sizing & Scalability - Part 3


Author: Thomas Bryant III, Vizioncore Senior Product Architect

In the first two parts of the series we've been talking about the basics of vFoglight and how the system components operate. In the previous post we were testing about 30 VMs, so now we've added another 70VMs bringing the total up to 100. Again, we can look at the JVM Memory Usage and Load Estimator to see how taxed the system is.

As you can see in the figures, there is data growth over time and periodic spikes in load. What is happening to cause the spikes? Garbage Collection, GC for short, is running on the vFoglight Management Server during those spikes. Essentially, as the JVM creates new objects, it uses memory to store the objects. Over time these objects become unused and the system could reclaim that bit of memory space to reuse for other purposes. That is what is happening during these spikes, GC is finding unused memory, clearing it out and allowing it to be reallocated. Garbage collection is akin to Memory reclamation in many senses.

Since the load is acceptable for 100 VMs, we will now go ahead and add in approximately 650 additional VMs. In total we're now going to be importing 809 objects. Objects are comprised of: Virtual Machines, ESX Hosts, Resource Pools, Folders, Clusters, Data Centers & vCenters.

Looking at the new load after adding the additional objects, we can observe that the load is maxing out the 2G of memory during GC periods. As the host is well undersized for a 64-bit application, it will be shutdown and more memory will be added.


Figure 3 - JVM Memory Usage & Load Estimator

After adding memory to the system, which is also highlighted in Figure 3, we can see load is once again reasonable. Essentially doubling the resources the vFoglight host, the load of the system has significantly dropped and performance has returned to normal.

vFoglight VM - Updated
OS - Windows 2003 R2 x86_64
vCPUs - 2
Memory - 4G (Changed from 2G)
Hard Drives - 3 VMDKs on Raid Group 2 (only VMDKs on the Datastore)
10G C:\ (OS Partition - 64k aligned)
5G D:\ (Swap Partition 4G Fixed size - 64k aligned)
30G F:\ (Application Partition - 64k aligned)
vFoglight 5.2.6 x86_64

In the next post I'll be talking about how we start to scale to something much bigger. We're already at 809 VMs/objects! Next we will do over 2500 & 5000 VMs/objects on our way up to over 10,000 objects!

Stay tuned,