# A Dynamic Decision Support System for Selection of Cloud Storage Provider
## 5 Results and Discussion
### Ranking Validation by Using AHP

Table 15: Column-wise Sum of Free Storage. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Repository** & **250,000 GB** & **100,000 GB** & **50,000 GB** & **25,000 GB** & **10,000 GB** & **1000 GB** & **500 GB** & **Priority** \\ \hline
**250,000 GB** & 0.48 & 0.53 & 0.55 & 0.41 & 0.33 & 0.25 & 0.23 & 39.6\% \\
**100,000 GB** & 0.24 & 0.27 & 0.31 & 0.36 & 0.29 & 0.25 & 0.23 & 27.8\% \\
**50,000 GB** & 0.07 & 0.07 & 0.08 & 0.15 & 0.18 & 0.20 & 0.18 & 13.1\% \\
**25,000 GB** & 0.06 & 0.04 & 0.03 & 0.05 & 0.15 & 0.14 & 0.18 & 9.1\% \\
**10,000 GB** & 0.05 & 0.03 & 0.02 & 0.01 & 0.04 & 0.11 & 0.13 & 5.6\% \\
**1000 GB** & 0.05 & 0.03 & 0.01 & 0.01 & 0.01 & 0.03 & 0.05 & 2.7\% \\
**500 GB** & 0.05 & 0.03 & 0.01 & 0.01 & 0.01 & 0.01 & 0.03 & 2.1\% \\ \hline \hline \end{tabular}
\end{table} 
Table 13: Priority of the Repository Parameter. Free storage, synchronization, trial period (if any), mobile access, and sharing are features of a cloud vendor's services. The cost of selected machines also varies with the selection of the cloud operating system, i.e., a system that costs $5 per hour with a Linux operating system might be $8 per hour with another operating system. Table 17 shows that Linux (due to better security) has priority over Windows and the Macintosh IOS. Table 18 shows column-wise sum of OS parameter values where Linux has twice the weight of Windows, and five times more than Mac due to its security and reliability. The same sequence of steps adopted for the above parameters are followed for further calculations; i.e., first of all, weights are defined, values are compared, converted to decimal form, and finally normalized by dividing each element to its column-wise sum. Most of the cloud providers offer a synchronization option so their clients can sync devices with the cloud storage. The major benefit of the synchronization is backup of data. By syncing, data can be transferred from the client's device to their cloud storage easily and rapidly. When a device like a mobile or laptop syncs with the cloud, a copy is created, and whenever changes take place on a laptop, data in cloud storage will also change. Table 19 shows values of the synchronization parameter as 'Yes' or 'No', where 'Yes' has the higher priority when compared to 'No'. Table 20 shows the Mobile Access parameter values and their priorities. Access to a mobile connection is an important feature, because nowadays users are using smart phones for social and official tasks. The mobile access parameter has two values of either 'Yes' or 'No', where 'Yes' has maximum priority when compared to 'No'. The trial period is an important parameter where users can use the limited services and functionality for a short period. Its priority values are shown in Table 21. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**OS** & **Linux** & **Windows** & **Mac** \\ \hline
**Linux** & 1.00 & 2.00 & 5.00 \\
**Windows** & 0.50 & 1.00 & 0.33 \\
**Mac** & 0.20 & 3.00 & 1.00 \\ \(\Sigma\) & 2.03 & 11.00 & 10.33 \\ \hline \hline \end{tabular}
\end{table} 
Table 17: OS Parameter Paired Comparison in Decimal Form. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Synchronization** & **Yes** & **No** & **Priority** \\ \hline
**Yes** & 0.90 & 0.9 & 90.5\% \\
**No** & 0.09 & 0.1 & 9.5\% \\ \hline \hline \end{tabular}
\end{table} 
Table 19: Priority Values for Synchronization. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**OS** & **Linux** & **Windows** & **Mac** \\ \hline
**Linux** & 0.49 & 0.18 & 0.48 & 61.1\% \\
**Windows** & 0.25 & 0.09 & 0.03 & 13.8\% \\
**Mac** & 0.10 & 0.27 & 0.10 & 17.5\% \\ \hline \hline \end{tabular}
\end{table} 
Table 18: Priority of OS Parameter Values. Finally, the consistency analysis is performed where the percentage is calculated for final weights relative to their aggregates. e.g., the CPU parameter criteria aggregate weight is 33%. The first is the value of sub-criteria when the CPU parameter is 24 cores and its weight percentage is 54%, i.e., the relative weight of 24 cores is 54% of 33%, which is 18.04.