Systems with Central Monitoring and Control for Data Center Infrastructure and the Effect of Video Frames in the Transmission Bandwidth

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1 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: Systems with Central Monitoring and Control for Data Center Infrastructure and the Effect of Video Frames in the Transmission Bandwidth Bexhet Kamo 1, Rozeta Miho 1, Vladi Kolici 1, Olimpjon Shurdi 1, Algenti Lala 1 1 Faculty of Information Technology, Polytechnic University of Tirana ALBANIA {bkamo, rmiho, vkolici, oshurdi, alala}@fti.edu.al Abstract Monitoring and control of power systems, cooling and environmental parameters in data centers, aim at a central monitoring of all elements of infrastructure, despite the different nature of all data and alarms. The architecture of monitoring and control system is analyzed in this paper taking into account the requirements for a centralized architecture. The bandwidth will be influenced more by monitoring cameras. The number of monitoring cameras, frame resolution, frame speed transmission and the level of compression, are taken into consideration in calculating the impact of video frames in the bandwidth. Index Term Monitoring, control, video frames, bandwidth I. INTRODUCTION To monitor and control a system, means to get information from the equipment or system, to analyze this information and to register it as an alarm or data. Further this information is stored and used to construct the history of monitored parameters. The process from this perspective, deals with managing the data center, while power system, cooling or environmental control parameters are a function of the creation of a reliable infrastructure and high availability for these parameters [1, 3, 4]. Power monitoring equipment, basically has to do with monitoring and control equipment such as UPS (uninterrupted power systems), PDU (power distribution panels), DC power supply systems and all other devices that are part of the AC and DC power. Regardless of the type of equipment monitored or controlled, the goal is to ensure an uninterrupted supply of data center [2]. Monitoring and control of cooling systems, or in general, HVAC systems (heating, ventilation and air conditioning systems), deals essentially with temperature control at the entrance and exit of equipment, mainly servers, in order determining the temperature of the work of HVAC equipment, and in order to eliminate condensation point in data centers or in specific equipment in particular [8, 11, 12]. It takes more importance in the case of temperature control of the "blade servers" in data centers, while these devices have specific requirements for temperature. The same control is also to monitor the relative humidity, taking care to maintain within the limit, the corresponding value. Processes of growth or lowering the level of relative humidity are automatic processes, controlled by the measured values and the logic of the functioning of the system. Monitoring and control of environmental parameters, has to do with monitoring and controlling temperature, humidity, air flow flow and water detection in the data center. The system also includes video monitoring, access control, and fire suppression system. There are a large number of sensors and parameters to be checked and this increases the complexity of monitoring and control system. The band width required for transmitting data from all devices and sensors, should be calculated, by taking into account the existence and considerable weight of video frames. II. THE ARCHITECTURE OF MONITORING AND CONTROL SYSTEM There are several methods for managing data center. One of management systems is the traditional system which controls each device separately, as in Fig. 1. The advantage of this method of control lies in the use of special monitoring programs thus eliminating the presence of a single point of failure in the system [7, 9, 10, 13]. This structure gives the possibility of use of different communication protocols as well as non-standard or unique interfaces in the system of monitoring and control. The main disadvantage of this system lies in the large number of individual programs, which do not allow real-time control of all systems. Central monitoring system is another option for control and monitoring systems. His principal scheme is given in Fig. 2. Obvious advantage of this architecture is that it monitors, from a single program, all subsystems, thus providing the possibility of real-time monitoring of the whole system. Disadvantage of this model is the presence of a single control program which is a single point of failure in the system. This

2 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: problem can be eliminated by using some additional elements in the system. The revised scheme with central monitoring system is presented in Fig. 3. standard communication interface, which should have any equipment. Such a thing is not always possible due to lack of standardization for interfaces and sensors. For this reason, we may use, architecture presented in Fig.4 Fig. 1. Traditional monitoring and control system In the revised scheme, the elements use the same communication protocol and communicate with the central program through LAN network [5, 6]. The presence of a communication card in any device, also allows separate control of their own, in case that the central program is damaged. Local data storage for a certain time, depending on the memory of communication card, eliminates the problem of access to data in the event of a breakdown of central monitoring system. The disadvantage of this configuration lies in the protocol or Fig. 2. System with central monitoring So the revised final scheme may include any sensor regardless of its interface. Sensors should be managed by a "device - access point" which will play the role of the interface between sensors and central monitoring system. Access Point, should be able to maintain for a period of time, data sensors, and enable the management of sensors from the central program, even locally through its SNMP interface.

3 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: Fig. 3. System with central monitoring in LAN Fig. 4. Central monitoring system with no standard interface sensors

4 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: III. THEORETICAL CALCULATION OF THE BANDWIDTH The bandwidth calculation shoul take into consideration all data generated from all devices and sensors. Since the video cameras are the main sensors that will effect mostly the bandwidth we consider only the effect of video surveillance cameras during the bandwidth calculation. The effect of other data is relatively small compared to video frames and it will occupy a relatively small bandwidth. The bandwidth calculation, for video transmission, is based on parameters that are deterministic in the size of video frames. By calculating the size of video frames and by selecting the frame rate and compression method, we calculate the bandwidth required for real time video transmission. Fig. 5, shows the graph that can be used for bandwidth calculation. Fig. 5. Flowchart for the bandwidth calculation, occupied by video frames The size of bandwidth is the bandwidth required for video frames transmission plus bandwidth required for environmental data and alarms. Since the bandwidth required for environmental data and alarms is relatively small, we study in

5 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: details only the bandwidth required for real time video transmission. Some other parameters that are not mentioned in the flowchart but that have an important role in real time video transmission are latency, caused by compression method selected and motion detection (an parameter of video cameras). The latency is an important parameter (that affects the real time video transmission) and for bandwidth optimization we should select between compression methods that offer an acceptable latency and a higher video compression value. There are a lot of compression methods like MJPEG, MPEG4, H264, etc. To optimize the bandwidth we may change parameters like: resolution and bit per pixel, frame rate and compression value. Frame resolution and bit per pixel value, are both related to the image quality. So if we intent to decrease the resolution or the bit per pixel value, we will lose the image quality. For video surveillance with normal quality is required to have a resolution of 640 x 480 and 24 bit per pixel value. Using matlab we can calculate the uncompressed frame size for different resolution values, as in Fig. 6. Fig. 6. Uncompressed frame size for different resolutions and bit per pixel values The frame rate is a parameter that takes values from 1 to 30 frames per second. As lower the frame rate as lower the bandwidth required. For video surveillance with a normal quality is required a frame rate of 25 frame per second, but based on the bandwidth value we can transmit using lower values, like 15, 10 or 5 frames per second. Using matlab, we may create an idea how the bandwidth changes for different frame rate values, as in Fig. 7 (the case is studied for images with 640 x 480 resolution and 16 bit/pixel value). The blue color graph, in Fig. 7, shows the bandwidth required for one video camera with frame rates from 1 to 30 frames per second, 640 x 480 resolution and 16 bit/pixel value. In order to optimize the bandwidth required, we compress the video frames. In Fig. 7, is showed the required bandwidth for different compression values. The bandwidth optimization can be done by changing the up mentioned parameters in a level that not change the minimum quality required.

6 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: Fig. 7. Bandwidth for one video camera for different frame rates and compression rates for a frame with 640 x 480 resolution and 16 bit per pixel value IV. RESULTS AND DISCUSSIONS Based on a real system design and in the theoretical calculations of bandwidth, is implemented in practice a monitoring and control system with central control and monitoring. The configuration of system is given in fig. 8. The system has two rooms and a control centre. Each room has a base station where video cameras and environmental sensors are connected. Besides, in the base stations are connected also sensors of alarms and data that comes from third party devices. Video, alarms and data collected to the bases station are transmitted, through the (1) Nr _ Sensors Frame' s rate(frame router, to the control centre. What should be solved next is the maximum number of video cameras for each base station. This number can be calculated based on the base station interface bandwidth. It is an Ethernet interface and offers 100Mbps and if the monitoring will be in a LAN (100Mbps) considering that around 10% will be used for other data there is 90% or 90Mbps to be used for video surveillance. The maximum number of video sensors can be calculated using formula (1). Bandwidth (bit/sec) s/ sec) x Resolution(pixels/ frame) x bit/pixel x comp. where comp. is the value of compression (for instance, if the compression is 10:1, comp. value is 0.1). Whether frame s parameters (that comes from the image processor) are set as: 640 x 480, 24 bit color, 25 frames per second, compression of 10:1, we see that one video sensor occupies around 19Mbps and for three video cameras, for example, is needed around 60Mbps. The number of sensors depends on resolution and frame rate and considering a fixed bit per pixel value and a fixed bandwidth the dependence (using matlab) is given in Fig. 9.

7 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: Fig. 8. Connection of the base station with sensors and information routing in the real system Fig. 9. Max. number of video cameras, 100Mbps network, different resolutions, 24bit per pixel and 20:1 compression value

8 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: A system designed for video, alarms and environmental real time monitoring, requires an accurate calculation of the bandwidth. The bandwidth will be shared for video cameras and for environmental sensors, but since the video occupies a large part of the bandwidth, we pay more attention to the real time video transmission, without considering bandwidth occupied by alarms and data of environmental sensors. In order to optimize the bandwidth, we take into consideration parameters that are deterministic in video size, like: resolution, bit per pixel value, frame rate, number of cameras in system and compression method. In this paper we showed a simple method to calculate and optimize the bandwidth, by changing: frame rate, number of video cameras, bit per pixel value, resolution and compression value. The parameter or parameters that will be change for bandwidth optimization depends on system requirements and for each case we should decide what to change. Whether there are strictly requirements for a parameter, let say frame quality, we keep as unchanged this parameter (in our case the minimum required resolution and bit per pixel value) and operate with other parameters (in this case: frame rate, number of video cameras and compression method). The selected compression method should not affect the video quality requirements so we may use MJPEG by compressing each frame or may use MPEG-4 or H264 for a higher compression [14, 15, 16]. The selection between compression methods will be based on latency and video quality allowed by system requirements. The graphics and dependencies showed above can be used to create an idea for the bandwidth required in a real case. REFERENCES [1] Torell. W, Avelar. V. Performing effective MTBF comparisons for data centre infrastructure. APC WP#112, Page 5 Page 12, [2] McCarthy. K. Comparing UPS system design configurations. APC WP#75, Page 3 Page 20, [3] Fairfax. S, Dowling. N, Healey. D. Reliability analysisof APC Infrastructure power system. APC WP#111, Page 5 Page 17, [4] Torell. W, Avelar. V. Mean time between failure: explanation and standards. APC WP#78, Page 10 Page [5] Kamo. B, Shehu A. [5] Kombinimi i serverit qëndror me monitorimet në kohë reale, bazë për siguri të lartë funksionimi, BSHT, Tiranë [6] Kamo. B, Shehu A. Realizimi i sistemit të fuqisë për qendrën e komunikimit tokë ajër të ANTA-s, BSHT, Tiranë [7] IEEE Emerald Book Series Staged Approach for SPDs in Data Center Applications, IEEE [8] Rasmussen. N. Power and cooling capacity management for data centers. APC WP#150, Page 3 17, [9] Zlatic. R. Monitoring Physical threats in the data center APC WP#102, Page 6-14, [10] Ives. T. Preventing data corruption in the event of an extended power outage. APC WP# 10, Page 4 6., [11] Bharat S. Shah Dynamic power management in the data center IBM power and cooling symposium Raleigh, NC [12] AMD. Power and cooling in the data center. AMD WP# 34146A [13] Schneider Electric. Integrated building management system in data centers. Schneider Electric WP -DC INTGMBS-US Page [14] GENETEC, white paper, Three Simple Ways to Optimize Your bandwidth Management in Video Surveillance, [15] Axis Communications, white paper - H.264 Video Compression Standard. Retrieved 2009, from Axis Communications Online: n_33085_en_0809_lo.pdf [16] Sony, Video Compression Technology - H.264 Explained. Retrieved 2009, fromsourcesecurity.com: rcesecurity.com/news/articles/co-3289-ga.2806.html