By consolidating servers coming off lease or near end of life, companies can save over 2 kilowatts by migrating to VMware® Virtual Infrastructure 3 software running on a Dell™ PowerEdge™ 2950 server.

The Dell Enterprise Technology Center measured workloads and power consumption on three older-generation servers: a Dell PowerEdge 2950, an HP DL380 G3, and an IBM x345. These servers were then migrated using VMware Converter 3 to see how many of the workloads could be consolidated onto a VMware Infrastructure 3 environment on a Dell PowerEdge 2950 server utilizing Intel® Xeon® x5355 Quad core processors.

The testing shows that eight of these workloads can be consolidated, resulting in over 500 percent power savings while achieving an equivalent amount of performance as the eight physical servers.

A comparison of consolidating from older HP server hardware to the Dell PowerEdge 2950 using VMware Virtual Infrastructure 3 indicates an average cost savings in power of $5,732.55 over three years.

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The following table shows the configurations of the servers used in the test.

	Dell PowerEdge 2650	IBM x345	HP DL380 G3	Dell PowerEdge 2950
Processors	Two Intel Xeon DP	Two Intel Xeon DP	Two Intel Xeon DP	Two Intel Xeon x5355 Quad Core
Processor Speed	3.06 GHz	3.06 GHz	3.06 GHz	2.66 GHz
Processor Cache Size	1 MB	1 MB	1 MB	8 MB
Front Side Bus	533 MHz	533 MHz	533 MHz	1,333 MHz
Memory	4 x 512MB PC2100 DIMMs	4 x 512MB PC2100 DIMMs	4 x 512MB PC2100 DIMMs	6 x 2GB PC5300 DIMMs
RAID	PERC 3/Di	ServeRAID 5i	HP Smart Array 5i+	PERC 5/i
Disk Drives	3 x 73 GB 10K RPM SCSI 3.5”	3 x 73 GB 10K RPM SCSI 3.5”	3 x 73 GB 10K RPM SCSI 3.5”	5 x 73GB 10K RPM 2.5” SAS
Power Supplies	Dual Redundant	Dual Redundant	Dual Redundant	Dual Redundant

The first three servers used for the physical tests were configured as similarly as possible. One thing that is interesting to note, the raw GHz speed of the older servers was more than the Dell PowerEdge 2950 we used for the consolidation.

This table shows the average scores for the three physical servers. Each test was run three times each on each physical server, and then averaged. That average is the number used below. Those averages were then averaged across all three to use as the baseline for the consolidation on the PowerEdge 2950 with ESX.

	DS2 Score (OPM)	Power Draw (Watts)	Avg CPU Util (%)
Dell PE 2650	3041.33	290.67	30.82
HP DL380 G3	2858.00	346.00	33.20
IBM x345	2450.67	278.67	28.91
Average	2783.33	305.11	30.98

Using the average numbers in the table above as the target, we were able to consolidate eight of these workloads onto the PowerEdge 2950 and achieve 80 percent CPU utilization as measured on the ESX server.

The following graphs show the OPM and wattage for the physical servers, and the end result after the consolidation.


Graph 1 - OPM measurement on physical and VMs - Roughly equivalent.


Graph 2 - Power measurements of both solutions - Lower is better.

Calculation of Savings Through Lower Power

Using the HP DL380 G3 as an example comparison, the savings is 2,328 watts as compared to the same solution virtualized on the Dell PowerEdge 2950 server. Power is sold by the kilowatt hour (kWh). Assuming that this solution will exist for an average three-year life of a server, the total kilowatt hours can be calculated.

2.328 kilowatts X 3 years X 365 days/year X 24 hours/day = 61179.84 kWh

Using the latest average price for commercial electricity from the U.S. Department of Energy , which is 10.05 cents per kWh as of August 2007, the total costs saved from using this solution can be calculated.

61,179.84 kWh X $0.1005 per kWh = $6,148.49

This result is the average cost of electricity across the entire U.S. Using the information from the government Web site, cost savings for different regions of the country can be determined.

If you happen to live in the New England area of the U.S., the average price for electricity is $0.1484 per kWh. In this case your savings would be $9,079.09.