Memory cost has consistently been one of the largest components of server expenditure, yet much expensive DRAM remains underutilized. What if you could double your virtual machine density and reduce your total cost of ownership by up to 40%?
VCF 9's Memory Tiering technology does exactly that. Today, we’re excited to share performance test results that demonstrate how this technology can transform data center economics through a new performance study.
In this blog post, we highlight key performance results from the paper, which show that Memory Tiering can double VM density with minimal performance impact. For a detailed understanding of how Memory Tiering works and more in-depth performance information, please refer to the full paper:
How Memory Tiering Improves Data Center Performance and Reduces Costs
In VCF 9, Memory Tiering provides virtual machines with a single logical memory space. However, beneath the surface, it manages Layer 0 (DRAM) and Layer 1 (NVMe) memory types based on virtual machine memory activity. Essentially, it works by keeping active, “hot” memory on DRAM and inactive, “cold” memory on NVMe.
From the VM’s perspective, this appears as a larger memory space. In the background, ESX dynamically manages the memory page placement across both DRAM and NVMe layers. This ensures optimal performance.
We conducted tests across various enterprise workloads to validate Memory Tiering’s performance. We used Intel and AMD servers with various DRAM configurations. VCF 9’s default DRAM:NVMe ratio is 1:1. We used this default 1:1 ratio in all tests.
| Benchmark | Workload | Results |
|---|---|---|
| Login Enterprise | VDI app | 2x VM density increase, 0-8% performance loss |
| VMmark | Enterprise apps | 2x VM density increase, 5% performance loss |
| DVD Store | Oracle Database | 2x VM density increase, less than 5% performance loss |
| HammerDB | SQL Server, MySQL | 2x VM density increase, 5-10% performance loss (SQL, MySQL) |
Login Enterprise: Virtual Desktop Performance
We used Login Enterprise to test VDI performance across a range of scenarios. In all tests, we were able to double the number of VMs on an ESX host while minimizing performance impact. For example, in a 3-node vSAN cluster configuration:
- We doubled the number of VDI sessions that could run on a 3-host vSAN cluster, from 300 (DRAM only) to 600.
- There was no performance loss compared to an equivalent all-DRAM configuration.
VMmark 3.1: Enterprise Application Performance
VMmark 3.1, which consists of multiple workloads representing a suite of enterprise applications, showed excellent results:
- The Memory Tiering configuration achieved 6 Tiles, while the pure DRAM configuration achieved 3 Tiles. This represents a 2x performance improvement.
- When comparing 1TB DRAM only vs. 1TB Memory Tiering, the performance loss was only 5%, even though Memory Tiering used slower NVMe.
HammerDB and DVD Store: Database Performance
Database performance is often the most demanding test for any infrastructure. We used HammerDB and DVD Store as workloads to test SQL Server, Oracle Database, and MySQL. With Memory Tiering, we were able to double the number of VMs with minimal performance impact. For example, Oracle Database with the DVD Store workload performed as follows:
- We were able to run 8 VMs on an ESX host with Memory Tiering, compared to only 4 VMs in a DRAM-only configuration, effectively doubling density.
- When comparing 1TB DRAM and 1TB Memory Tiering configurations, we observed a performance loss of less than 5%.
Monitoring Memory Tiering on ESX Hosts
You should monitor two key metrics to ensure good performance with Memory Tiering:
- Keep active memory at 50% or below of DRAM for optimal performance.
- Monitor NVMe device read latency. Below 200 microseconds is optimal for performance.
Transforming Data Center Economics
Memory Tiering offers a new approach to memory configuration:
- It can save up to 40% TCO by reducing DRAM requirements.
- It operates transparently, requiring no changes to applications or guest operating systems.
- It enables a 2x VM density increase across different workload types.
- It works within a flexible infrastructure that can adapt to changing workload demands.
Memory Tiering is now available in VCF9. Download the full performance study report for a deeper dive into our testing methodology, detailed performance results, and implementation best practices: