Building the 2012 AnandTech SMB / SOHO NAS Testbed

The virtualization infrastructure in our testbed involved running Hyper-V on Windows Server 2008 R2. The benchmarking programs include IOMeter 1.1rc1 / Dynamo and Intel NASPT. While the former is used to test multi-client performance, the latter is used for testing the single client scenario. IOMeter itself runs on the host machine, while Dynamo instances run on each VM. Intel NASPT is run from one of the VMs only. Twelve guest machines were set up with similar configurations as below:

Each VM gets one vCPU. By default, each VMs gets 2GB of RAM. However, when performing the robocopy tests to transfer a Blu-ray folder structure to and from the NAS, we choose to increase the amount of memory in that particular VM to 24GB (since only one VM is active in this case). This enables the creation of a RAM disk to house the folder structure (10.7GB). Under all scenarios, the host OS has a 32GB RAM disk mounted at startup. The RAM disks were created and mounted with Passmark Software’s free utility, OSFMount.

Two network interfaces are set up for each VM. While one of them connects to the NAS through one of the physical LAN ports provided by the Intel ESA-I340 and gets its IP address through DHCP in the 192.168.1.x subnet, the other is an internal network between the VMs and the host machine. With the host taking the static IP 10.0.0.1, each VM’s internal network interface is set up with a static IP of the form 10.0.0.x, with x between 2 and 13. The 32GB RAM disk mounted on the host is shared over this internal network for the VMs and the host to exchange information on the fly.

The guest OS on each of the VMs is Windows 7 Ultimate x64. The intention of the build is to determine how the performance of the NAS under test degrades when multiple clients begin to access it. This degradation might be in terms of increased response time or a decrease in available bandwidth. Both of these can be measured using IOMeter. While IOMeter is the controlling program installed in the host, each of the VMs run the Dynamo workload generator component. Dynamo and IOMeter communicate through the internal network to ensure that there is no effect on the benchmark runs.

Four distinct workloads corresponding to the storage performance evaluation metrics outlined here were set up to run on each machine. In the first pass, only the first VM runs the workload and reports the results. In the second pass, the first two VMs run the workload and report back and so on, till we conclude the IOMeter benchmark runs with all the twelve VMs running workloads simultaneously and reporting results. Fortunately, all the synchronization aspects are handled by IOMeter itself.

Manually running the dynamo process on each VM and restarting it after the completion of each pass is definitely a cumbersome process. To make things a little easier, we installed SSH servers on all the VMs. Bitvise SSH Server was our software of choice for the ease of use and configurability. After installing Strawberry Perl (on the host as well as all the VMs), we developed a small script to SSH from the host into each of the VMs in order, mount the NAS share and run Dynamo multiple times in sequence. The ICF files used in each of the twelve passes are available for download here.

In our review of the Western Digital Red hard drive, we used this testbed to fill up the NAS to varying levels. For this purpose, some files and folders were copied onto the RAM disk in the host which was shared over the 10.0.0.x internal network. This shared disk was mounted on all the VMs. A Perl script to copy over the contents from the mounted RAM disk (as many times as necessary to achieve a required fill percentage) to the NAS drive was processed. This simulates the NAS being subject to activity from multiple clients in the process of getting filled up.

In the next two sections, we will take a look at the sort of results that this testbed is able to provide us in terms of evaluating NAS performance.