Information Technology Reference
In-Depth Information
ment capabilities such as security services, fire-
walls, and intrusion detection systems to include
their cloud resources. The billing of such services
is based on the number of VPN connections per
hour and the data transferred.
The metrics used to bill IaaS and PaaS services
are presented in Table 2.
and hosted SaaS solutions will find very useful
to predict software development costs, as these
costs define all relevant on-going costs such as
maintenance, training, upgrades and also costs
related to infrastructure.
A. IT Infrastructure Costs
Traditional Software and Systems
Costs
When estimating software development and
maintenance costs, IT infrastructure costs should
also be accounted. IT costs are non-negligible as
usually they stand up to 60% of Total Ownership
costs (Gray, 2003), (McRitsie, 2008). Unlike soft-
ware development estimation, IT estimation is a
simpler process as infrastructure and services are
more tangible. The cost drivers that influence IT
This Section discusses the costs related to IT
infrastructure and software development for an
application based on on-premise assets. Com-
panies that possess their own IT department
have the dilemma of selecting between in-house
Table 2. IaaS and PaaS billing metrics
Type of Metric
Metric
Explanation
Charges and current SaaS vendors
Hardware and application metrics
No Instances of
servers
Number of servers.
The prices are based on the operating system and the software
installed on the server. The pricing models depend on the
provider and can be calculated based on the usage per hour or
per month.
CPU
Level of CPU usage
The CPU usage may is calculated in hours or cores.
Bandwidth
Incoming, outgoing
bandwidth
The gigabytes transferred from and to the cloud measured in
gb/ per unit of time
RAM
Megabytes, Gigabytes
RAM memory committed measured in MB or GB /per unit of
time
Storage metrics
Data Storage
Hard disk storage,
Terabytes
GB or TB/ per unit of time
Data transfer
Amount of data
transferred in different
regions
GB or TB/ per unit of time
Data requests
Copy, get, put, list
Number of requests per month
Networking services
No of VPN connec-
tions
Virtual Private Net-
work that will bridge
the cloud to private
infrastructure
Number of VPN connections per hour
Monitoring opera-
tions
Monitor the cloud
computing resources,
statistics
A charge based on the number of instances monitored per hour
IP addresses
Additional public IP
adresses
Number of IP addresses generated
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