# Fog Computing for Smart Cities' Big Data Management and Analytics: A Review
## 5 Toward Fog-Based Smart City Data Management and Analytics
### Deploying Data and Software in Fog Nodes and Cloud Servers  
The traditional method for smart city applications is often to install software tools locally and perform in-house analysis. However, with recent advances in cloud and fog computing, the growing trend is to store data and deploy software in fog/cloud to make them available as a service (i.e., DaaS for data and SaaS for software). Depending on the kind of data analysis required by the application, data can be deployed in the fog or the cloud. Time-sensitive analysis, which requires low latency, would use data stored in the fog. However, non-time-sensitive analysis would use data deployed in the cloud to gain in-depth insights.  
Currently, most smart cities store only a small amount of their data in the cloud. The bulk of their data is still in traditional databases. As an increasing number of projects, such as healthcare and transport, deploy IoT solutions to enhance their services, they generate massive data volumes. Data storage, sharing, and analysis would be required at the fog/cloud level. Transferring massive amounts of data from smart cities to cloud servers is a significant bottleneck. At present, it is not uncommon to physically ship large-capacity hard drives, such as Amazon Web Services (AWS) Snowball devices, to the cloud data center. It is recognized that when data to be moved to the cloud are on a terabyte scale and beyond, it is better to ship them to the cloud provider rather than uploading them. Direct uploading of large volumes of data to the cloud may require an unacceptable amount of time, even on a hundred Mbps Internet connections and faster. The technique to choose would depend on many factors, including the size of the data to be transferred, the speed of Internet connection supported between the source and destination servers, the sustained speeds of copy-in/copy-out supported by the storage device and the source and destination drives, the monetary cost of data transfer and, to a lesser extent, the cost of shipping and transit time. Currently, a promising technique for transferring large volumes of data to fog/cloud servers is using innovative new transfer technologies such as IBM Aspera's high-speed file transfer technology (Aspera FASP). This technology significantly speeds up file transfers and outperforms traditional file transfer technologies such as File Transfer Protocol (FTP) and Hypertext Transfer Protocol (HTTP). Several large companies rely on this technology for the high-speed transfer of large volumes of data. For example, BT Sport uses Aspera technology to power its intense file-based production workflows. Furthermore, other technologies, such as data compression, are available to facilitate the transfer of large amounts of data [27; 28].  
Answering the smart city's most important and most complex questions often involves the use of multiple tools. Most of the software tools used by different city departments are designed for workstations (rather than the cloud) and therefore are not delivered as cloud-based web services, making it impossible to run complex analysis tasks. As a result, many smart cities' continued efforts have only used a small portion of the available cloud-based tools. To store, share and analyze big data with lower cost and increased efficiency in smart cities, it is essential to make a large volume of smart city data available to the public, as well as a wide variety of software applications in the fog/cloud, provided as services via the internet.