In a previous white paper, a comparison between Dell 2-socket and HP 4-socket servers running a series of workloads on VMware® ESX Server was made. At the time of testing, the two systems used were the most powerful available configurations available for the Dell™ PowerEdge™ 2950 and HP Proliant DL585. This timing means the comparison was between two 8-core servers: a two-socket, quad-core server and a four-socket, dual-core server. The conclusion of that paper was that the two-socket, quad-core server was better for virtualization based on performance, price/performance, and performance per watt.

The Dell PowerEdge R900 is a four-socket, quad-core server with 16 cores total. This number of cores puts it more on par with the Dell 2950 two-socket server in terms of processing power per socket, as both the PowerEdge 2950 and PowerEdge R900 are using quad-core processors. To determine how this current-generation four-socket server compares with the Dell two-socket server in the previous test, a PowerEdge R900 with four Intel® Xeon® X7350 processors and 128 GB of RAM was run through the same tests in June 2008. The test environment from the previous test still existed, so the test was reproduced in every way. The same virtual machines (VMs), the same storage, and the same DVD store test application were used. The table below summarizes the configuration of the PowerEdge R900 used in the new test and the PowerEdge 2950 from the previous tests.


PowerEdge 2950 PowerEdge R900
Virtualization software VMware ESX Server 3.0.1 VMware ESX Server 3.5
Processor Two quad-core Intel Xeon X5355 processors at 2.66 GHz with 8MB cache (shared) Four quad-core Intel Xeon X7350 processors at 2.93 GHz with 8MB cache
Frontside bus 1,333 MHz 1,066 MHz
Memory 16 GB (8x 667 MHz fully buffered 2GB DIMMs) 128 GB (32x 667Mhz fully buffered 4GB DIMMS)
Internal disks Two Serial Attached SCSI (SAS) 146 GB, 15,000 rpm drives Two Serial Attached SCSI (SAS) 73 GB, 15,000 rpm drives
Network interface card (NIC) Two 10/100/1,000 Mbps internal NICs Two 10/100/1,000 Mbps internal NICs
Disk controller PERC 5/i PERC 6/i

Please see the previous paper for configuration details on the storage, VMs, and DVD Store test application, which were kept the same for this test.

Testing

Only the Microsoft® SQL Server® and SUSE® LAMP (Linux, Apache, MySQL, PHP) tests were repeated for this update. As this is only a quick update and not a complete performance study, it was determined that two data points would be enough.

To have a common point for comparison, the number of VMs was held constant with respect to the earlier paper. Specifically 32 SQL Server VMs and 44 MySQL VMs were used for testing on the PowerEdge R900 to match the number of VMs that originally drove the PowerEdge 2950 to approximately 85 percent utilization. The workload on each VM was then increased to drive CPU utilization close to 85 percent on the PowerEdge R900, which was done by increasing the number of DVD Store user threads for each VM. For the SQL Server VMs and the MySQL VMs, the number of threads was tripled to drive the server to approximately 85 percent CPU utilization.


Results

The performance of the PowerEdge R900 is much better than the performance of the PowerEdge 2950 tested in the earlier paper. This result is expected because it’s a much newer server and has twice as many cores and four times as much memory. Not surprisingly, given that there are twice as many processors, power consumption is also much higher. The trade-off results in a performance per watt number for the SQL Server and MySQL tests that are 10 percent and 23 percent better, respectively, for the PowerEdge R900; although, the raw performance of the PowerEdge R900 is well over twice that of the PowerEdge 2950. The complete results are in the tables below.


SQL Server VMs Test PowerEdge 2950 with Intel Xeon X5355 PowerEdge R900 with Intel Xeon X7350
VMs
32
32

User Threads Per VM
4
12

% CPU Utilization
85
86

Orders Per Minute
29346
72386

Avg Watts
449
1007

Performance Per Watt
65
72
R900 is 10 % better


SLES LAMP VMs Test PowerEdge 2950 with Intel Xeon X5355 PowerEdge R900 with Intel Xeon X7350
VMs
44
44

User Threads Per VM
1
3

% CPU Utilization
86
88

Orders Per Minute
9852
27582

Avg Watts
447
1019

Performance Per Watt
22
27
R900 is 23 % better


Conclusions

An increase in performance per watt in the range of 10 to 20 percent shows that the new Dell PowerEdge R900 is not only more powerful than the previous generation PowerEdge 2950, but is also more efficient.