Chapter 4 - DSpace at Waseda University

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Chapter 3 hardware such as SoC (Systems on Chip) technology, embedded software became very complex software. These technologies cause many innovations such as smartphone, PDA, netbook and tablet PC, etc. On the other hand, these innovations make system complicated, and increases errors and bugs continuously when the developing of the embedded systems. Moreover, these problems need a lot of time and effort to fix up. In addition, it became very important to way to fix up the errors and bugs because it is closely related to the performance and stability of the system. Therefore, most developers and system managers are analyzing event logs to figure out the best solutions for the problems. 3.1 Event log Event logging and event logs monitoring play an important role in modern IT systems. Today, many applications, operating systems, network devices, and other system components are able to log their events to a local or remote log server. For this reason, event logs are an excellent source for determining the health status of the system, and a number of tools have been developed over the past 15-20 years for monitoring event logs in real-time [45]. 3.1.1 Event logging The events that occur in the system depend on the status of the system, it is always changing. When a system component encounters an event, the component could emit an 22
23 Chapter 3 event message that describes the event. For example, when a disk of a server becomes full, the server could generate a time stamped “disk full” message for appending to a local log file or for sending over the network as an SNMP trap. Event logging is a procedure of storing event messages to the event log, where event log is a regular file that is modified by appending event messages. (Although sometimes databases of event messages are also called event logs) Log client is the system component that emits event messages for event logging. In this thesis, the term event has often been used for denoting event messages when it is clear from the context. In modern IT systems, event logs play an important role: � Since in most cases event messages are appended to event logs in real-time as they are emitted by system components, event logs are an excellent source of information for monitoring the system, � Information that is stored to the event log can be useful for analysis at a later time, e.g., for audit procedures or for retrospective incident analysis. Event logging can take place in various ways. In the simplest case the log client keeps the event log on a local disk and modifies it when an event occurs. Unfortunately, event logs will be scattered across the system with this logging strategy, each log possibly requiring separate monitoring or other analysis. Furthermore, the strategy assumes the presence of a local disk which is not the case for many network nodes (e.g., switches and routers). Figure 3.1 centralized logging infrastructure. This is the flow chart of the event log which
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Chapter 5 Figure 5.13: Result of an
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Chapter 5 Figure 5.16: Result of ex
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Chapter 5 5.6 Summary We analyzed l
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Chapter 6 In embedded systems, ther
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Chapter 6 Figure 6.1: Real-Time Arc
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Appendix A.1 RTOS Commonly, a goal
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Appendix software, real-time OS mus
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Appendix critical task and non-crit
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Appendix � Portability CABI shoul
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Bibliography [1] L. Abeni, A. Goel,
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Bibliography [21] C. Yuan, N. Lao,
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Bibliography [38] Magdalena Balazin
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Bibliography [56] Balakrishnan, S.;
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Acknowledgements I would firstly li
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