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Principled Technologies, Inc.: Initial investment payback analysis: Dell PowerEdge R710
solution with VMware ESX vs. HP ProLiant DL385 solution
Appendix C – Payback period calculation
In calculating the estimated payback period, we assume that investment costs occur at the beginning of the year
and we spread annual costs evenly throughout the year. Dell provided the components of the Dell PowerEdge
R710 solution. The investment costs include the following:
• Intel Xeon Processor X5550-based Dell PowerEdge R710 server with 96 GB of memory and two four-
core processors. The list price for this server is $16,152.
• Dell™ EqualLogic™ PS6000XV storage with 16 450GB 15,000 RPM disks. The list price of the storage
array is $55,000. We assign half ($27,500) of the storage array costs to this solution based on the
assumption that the array is a resource that can be shared with other workloads.
• Migration costs. We assume a migration cost of $905, based on our estimate of 12 person hours required
for planning and migration tasks at a burdened hourly rate of $55.61, totaling $667, and a prorated
VMware training cost of $238 for the server administrator.
Figure 10 shows the payback calculation for the Dell PowerEdge R710 solution and the seven HP ProLiant
DL385 solutions.
HP ProLiant
DL385 solutions
Dell PowerEdge
R710 solution
Difference
One-time initial investment (includes server,
storage hardware, and migration costs)
$0.00 $44,556.55
$44,556.55
(HP ProLiant
DL385 is lower)
Monthly cost (annual costs divided by 12; includes
hardware support, maintenance and service
contracts, software licenses and support
agreements, facility costs, energy costs, and
management costs)
$3,413.67 $879.31
$2,534.36
(Dell PowerEdge
R710 is lower)
Payback period 17.6 months ($44,556.55/$2,534.36=17.6)
Figure 10: Payback calculation for the Dell PowerEdge R710 solution and the seven HP ProLiant DL385 solutions.
The server and storage hardware costs for the Dell PowerEdge R710 solution included the list price of the Dell
PowerEdge R710 server and the list price of the Dell EqualLogic PS6000 storage solution multiplied by the 50
percent of that solution that the test databases require. For the HP ProLiant DL385 solution server, these costs
included the replacement costs for failed disks. We made the following assumptions in estimating these costs:
• The enterprise would dedicate the entire newer Dell PowerEdge R710 server to the tasks that the servers
it was replacing carried out; we therefore included the entire cost of the newer Dell PowerEdge R710
server in our analysis.
• As they were in our tests, the log files would be on two internal disks on each server.
• Other servers in the data center would share the storage in the Dell PowerEdge R710 solution and the
enterprise would apportion storage costs based on the percentage of the storage solution used. We
estimated that the high-demand DS2 workload we used in our cost calculations would use less than 10
percent of the storage capacity of the Dell EqualLogic PS6000 storage solution but would require most of
the IOPS capacity of the storage during peak load. Balancing the available storage and IOPS, we
estimated that half the storage capacity would be available for low-demand storage or for off-hours
processing.
• The enterprise would dedicate both the HP ProLiant DL385 solution servers and storage enclosures to
the tasks our benchmark tests model.
• The migration costs included an estimate of staff time to migrate software and data from the HP ProLiant
DL385 solution to the newer solution.
We made the following assumptions in estimating the support, maintenance, and service contract costs for
hardware: