Peter Bosch. Mixed-media file systems. PhD thesis, University of Twente, June 1999.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....overflow. Korst et al. 9] compared a number of disk scheduling algorithms that can be used in a multimedia server for sustaining multiple variable bit rate (VBR) data streams and paid attention to the bu#er under and overflow. We assume a constant bit rate for the streams. According to [1] and [5] this is acceptable for variable bit rates when bu#ering big chunks of data. 3 Early Quantum EDF tasks A PIT is a promoted QEDF task, that executes its new invocations as soon as possible. We need a PIT as an intermediate step to transform a QEDF task into a EQT. To describe this transformation ....

Peter Bosch. Mixed-media file systems.

....does not provide random access, the HMA stages data in a secondary storage cache from where it is delivered to the applications. The implementation of the secondary storage cache is outside the scope of the toolbox. At present we use a normal Linux file system, but we are planning to use Clockwise [2] in the future to guarantee real time access to the data in the cache. The toolbox is implemented in Java, except for some functionality which is operating system dependent. The drive controllers use the Java Native Interface (JNI) to call C functions on Linux in order to open and close the ....

P. Bosch. Mixed-media file systems. PhD thesis, University of Twente, June 1999.

....video, it can also be music. Figure 2 shows the flow of data from the jukebox to the end users. We must guarantee that the data is promoted from one storage level to the next in time. JEQS guarantees that the data is promoted from tertiary storage to secondary storage in time. In turn Clockwise [3] provides real time access to data stored in secondary storage, which is used as cache, and finally RTnet [9] provides real time guarantees for the use of a local area network. The VoD system is a special case of the hierarchical multimedia archive (HMA) presented in [16] The VoD system can ....

....the user does not run out of data. The period depends on the bandwidth required by the request and the bandwidth offered by the drive. Without loss of generality we can assume that the data is consumed with a constant bit rate, because the buffer size is large. Anastasiadis et al. 1] and Bosch [3] show that a variable bit rate stream can be treated as a constant bit rate stream when the buffer size is large enough. This model creates as output a set # = # 1 , # n of periodic tasks to schedule. Each task # i needs to be executed only a finite number of times. We compute the ....

Peter Bosch. Mixed-media file systems. PhD thesis, University of Twente, June 1999.

....of the overall system and the mechanisms used to promote data between contiguous storage levels. The focus of this paper is Promote IT (Promote In Time) the jukebox scheduler that guarantees the in time promotion of multimedia data from tertiary storage to secondary storage. In turn Clockwise [2] provides real time access to data stored in secondary storage, which is used in HMA as cache, and finally HOTnet [10] provides real time guarantees for the use of a local area network. The main goal of Promote IT is to guarantee that the data is buffered in secondary storage by the time ....

P. Bosch. Mixed-media file systems. PhD thesis, University of Twente, June 1999.

....or dvd rom, or rewinding before unloading in the case of tapes. These characteristics of the drives influence the load and unload times. Another issue that influences the load and unload times is the distance to the drive of the slot where the cd is kept. Based on the experience of Clockwise [2] we use a model of the hardware to predict the time the system will need for operations on robots, drives and media. We have validated the model against our actual hardware. We use this model both for constructing the schedules and as a simulator in our experiments. To give a feeling of the scale ....

Peter Bosch. Mixed-media file systems. PhD thesis, University of Twente, June 1999.

....tailor the circuits so that the wires are as short as possible and all the signals get from their originating point to the right place at exactly the right time. Then, the software designer must carefully determine in detail what the devices are capable of before designing a multimedia system [11]. There are many subtle device issues that can influence the overall I O performance of a system. When, after a lot of fine tuning, finally the system is running satisfactory, performance problems can arise easily when the (hardware or software) configuration of the system is (slightly) changed, ....

Bosch P.: "Mixed-media file systems", Ph.D. Thesis University of Twente, June 1999.

....retrieval of data is essential, as the amount of data in the file server is huge. e.g. one hour video in DVD quality measures several gigabytes of data. A side e#ect of this all is that peripherals are shared by all. A good starting point for this research is the work done in our group by Bosch [1]. We will assume that such a storage server is present in the system. Because real time data conversion is a high level service in the system, our assumption does not interfere with other objectives (see figure 2) C. Resources Even small appliances (resource lean) like a temperature or light ....

H.G.P. Bosch, Mixed-media file systems, Ph.D. thesis, University of Twente, ISDN 90-365-1277-8, 1999

....pool of schedulable requests. The tradeoff between these two approaches is studied in detail in [26] where the authors show the merits of host scheduling. Recent work on extensible kernels also advocates fine grain control of disk resources for maximum flexibility and adaptivity (e.g. Nemesis [2]) The file system design has a significant effect on disk performance as it determines the data layout and physical access patterns. Unix FFS [18] statically allocates regions of the disk for inodes, and tries to locate data and metadata in rotationally optimal positions. However, metadata ....

P. Bosch. Mixed Media File Systems. PhD thesis. University of Twente, 25 June 1999.

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Peter Bosch. Mixed-media file systems. PhD thesis, University of Twente, June 1999.

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