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All the necessary information from DataCenter Data Center side can and should be addressed as a set of simple, unambiguous questions. These questions in turn can be divided roughly in to three subsets, based on the goal they are helping to achieve. Each subset can be expressed as a more general "umbrella question":
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- First question of above three, is vital to gather the information that affects following topics in Warren development:
- Architectural decisions:
- which external libraries, components and standards to use to cope the requirements of majority of DCs DC in target group?
- How to design the functionality in component systems, so that the we provide the value we claim to be offering, without causing the decrease in quality of services and processes existing there before Warren adoption?
- Marketing content and business value:
- Can we actually offer the functionality we are claiming to be , offering?
- Can we offer the functionality in sufficient level of reliability?
- Are we doing it in a sensible way, e.g. the development effort is comparable to the actual value the development result is providing?
- Are all the features and functionality we are/will be providing also in correlation with the actual requirements?
- Architectural decisions:
Conflicting nature in
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service requirements
To enhance the analysis result and make it directly usable as an input to development process, let's partition the hypothetical DC stack (hardware, firmware, software) into functional domains that have common properties to according Warren components. Two of DC functional stack domains they have before Warren adoption are more influential than others, both future development- and adoption process-wise to us. These are Network and Storage. They are also tightly coupled, as decisions in one domain heavily depend on properties of the other. If analyzed, the connection between these two domains is expressed best in decision making process, as two fundamental trade-offs:
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- Availability in this context denotes:
- Spacial - data or service is concurrently available to recipients/consumers in different locations rather than just one (many VMs Virtual Machines using same database that resides in distributed storage)
- Temporal continuity - data or service is kept available even in case of soft- or hardware failures ("High Availability")
Both of these aspects may seem very desirable, especially in cloud computing, but the downside is delivery speed in various forms. For example distributed storage without high-end hardware may not have sufficient latency for storage-sensitive applications. Also, to keep the applications availability rate high, there are software and several levels of hardware redundancy involved that means buying additional devices and keep them constantly running. - Locality denotes the physical distance of some functional domain from compute resource (local storage vs distributed storage)
While High Availability metrics are received by involving distributed and redundant resources, locality is also not free from redundancy cost, however it is usually the one of sub-server level, so definitely less expensive. Local storage has also much lower latency, but total capacity is very limited and, as data on this storage is not available to outer devices without additional control and services, it introduces additional data duplication need in addition to one that is meant for "High Availability".
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