But before that let's underscore that Clouds are not in the skies but rather in huge weird buildings with special Physical and Infrastructure security likes this Data Center in Georgia:
You can see some real old fashion clouds above the building but they are not what we are talking about. Inside Data Center you can see a lot of Racks, each with 20+ servers which are, together with all secure network and application infrastructure contain these modern "Clouds":
Attributes and Parameters of mature SaaS (and VaaS as well) include:
- Multitenant and Scalable Architecture (this topic is too big and needs own blogpost or article). You can review Tableau's whitepaper about Tableau Server scalability here: http://www.tableausoftware.com/learn/whitepapers/tableau-server-scalability-explained
- SLA - service level agreement with up-time, performance, security-related and disaster recovery metrics and certifications like SSAE16.
- UI and Management tools for User Privileges, Credentials and Policies.
- System-wide Security: SLA-enforced and monitored Physical, Network, Application, OS and Data Security.
- Protection or/and Encryption of all or at least sensitive (like SSN) fields/columns.
- Application Performance: Transaction processing speed, Network Latency, Transaction Volume, Webpage delivery times, Query response times
- 24/7 high availability: Facilities with reliable and backup power and cooling, Certified Network Infrastructure, N+1 Redundancy, 99.9% (or 99.99% or whatever your SLA with clients promised) up-time
- Detailed historical availability, performance and planned maintenance data with Monitoring and Operational Dashboards, Alerts and Root Cause Analysis
Disaster recovery plan with multiple backup copies of customers’ data in near real time at the disk level, a
multilevel backup strategy that includes disk-to-disk-to-tape data backup where tape backups serve as a secondary level of backup, not as their primary disaster recovery data source.
- Fail-over that cascades from server to server and from data center to data center in the event of a regional disaster, such as a hurricane or flood.
While Security, Privacy, Latency and Hidden Cost usually are biggest concerns when considering SaaS/VaaS, other Cloud Concerns surveyed and visualized below. Recent survey and diagram are published by Charlie Burns this month:
Other survey and diagram are published by Shane Schick in October 2011 and in February of 2013 by KPMG. Here are concerns, captured by KPMG survey:
As you see above, Rack in Data Center can contain multiple Servers and other devices (like Routers and Switches, often redundant (at least 2 or sometimes N+1). Recently I designed the Hosting Data VaaS Center for Data Visualization and Business Intelligence Cloud Services and here are simplified version of it just for one Rack as a Sample.
You can see redundant network, redundant Firewalls, redundant Switches for DMZ (so called "Demilitarized Zone" where users from outside of firewall can access servers like WEB or FTP), redundant main Switches and Redundant Load Balancers, Redundant Tableau Servers, Redundant Teradata Servers, Redundant Hadoop Servers, Redundant NAS servers etc. (not all devices shown on Diagram of this Rack):