J. Wolf, "The Placement Optimization Program: A Practical Solution to the Disk File Assignment Problem", SIGMETRICS '89, ACM, May 1989.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....in a data center. It uses simple metrics for performance such as number of active connections and overall response time; it is similar in nature to the automatic loop in section 5.2.3 in its management of compute and network resources. Existing solutions to the file assignment problem [DF82, Wol89] use heuristic optimization models to assign files to disks to get improvements in I O response times. The work described on file allocation in [GWS91, SWZ98] will automatically determine an optimal stripe width for files, and stripe those files over a set of homogeneous disks. They then balance ....

Joel Wolf. The placement optimization program: a practical solution to the disk file assignment problem. In Proceedings of the ACM SIGMETRICS Conference, pages 1--10, May 1989.

....[AKYU95] argued for optimal placement of blocks instead of cylinders, and reserved space in the middle of the disk in which to replicate the most accessed blocks. Simulations were veri ed with implementation, and rearrangement with orthogonal techniques such as scheduling were discussed. [WOLF89] used two heuristic optimization models in combination with a queuing network model to implement a disk arrangement that reduced I O response time. YIN98] exploited determinism in application loading by rearranging the blocks involved in launching a program, comparing several di erent heuristic ....

J. Wolf, The Placement Optimization Program: A Practical Solution to the Disk File Assignment Problem, Performance Evaluation Review, Vol. 17 (1), May 1989.

....[28] bin packing heuristic. Minerva [2] extends Forum to handle disk arrays. The comparison with Minerva, and hence a superset of Forum can be found in Section 4.1 where we show that Ergastulum is faster and generates as good or better designs. Existing solutions to the file assignment problem [11, 35] use heuristic optimization models to assign files to disks to get improvements in I O response times. The file allocation schemes described 23 in [12, 24] automatically determine an optimal stripe width for files, and stripe those files over a set of homogeneous disks. They then balance the load ....

J. Wolf. The placement optimization program: a practical solution to the disk file assignment problem. In ACM SIGMETRICS Conference, pages 1-- 10, Berkeley, CA, May 1989. 25

....for writes, respectively. To improve read performance, one can occasionally re organize the data blocks to place popular blocks near the center of the disk and cluster blocks that tend to be accessed together. Ruemmler91] uses an open subsystem model to evaluate the benefits of such an approach. [Wolf89, Vongsathorn90], on the other hand, measure this approach by implementing it in real systems. To improve write performance, one can write data blocks to convenient locations (i.e. locations that are close to the disk s read write head) and change the mapping, rather than writing the data to the location ....

J. Wolf, "The Placement Optimization Program: A Practical Solution to the Disk File Assignment Problem", ACM SIGMETRICS International Conference on Measurement and Modeling of Computer Systems, May 1989, pp. 1--10.

....It is also based on an iterative loop, like Hippodrome, but it focuses on allocating computational resources. Its resource allocation framework is based on an economic model that factors in the tradeoffs between the service quality and the cost. Existing solutions to the file assignment problem [13, 34] use heuristic optimization models to assign files to disks to get improvements in I O response times. The file allocation schemes described in [16, 28] will automatically determine an optimal stripe width for files, and stripe those files over a set of homogeneous disks. They then balance the ....

J. Wolf. The placement optimization program: a practical solution to the disk file assignment problem. In ACM SIGMETRICS Conference, pages 1--10, Berkeley, CA, May 1989.

.... of optimizing some objective such as communication overhead or reliability [3, 10, 19] Our work is most closely related to the variant where files characterized by size and access rate are placed on a given set of storage devices, with the aim of minimizing access latency or maximizing throughput [24]. However, these approaches do not design the system that will efficiently provide the needed quality of service; they make use of a given system so that an objective function is maximized, regardless of application requirements. We also allow a richer characterization of application behavior than ....

J. Wolf. The placement optimization program: a practical solution to the disk file assignment problem. In Proc. SIGMETRICS, pages 1--10, May 1989. 27

....bottleneck, the second attempts to minimize disk head movement, and the third attempts to maximize throughput for large files. The second approach, data clustering, is discussed in more detail in Section 2.5. For computers with a single type of secondary storage, load balancing is well understood [120]. By measuring past file activity, the system attempts to balance the total activity for each device by moving files from disk to disk. Load balancing is generally not done in UNIX systems. In the near future, with the advent of (fast) electronic disks and (slow) optical jukeboxes, the potential ....

J. Wolf. The placement optimization program: a practical solution to the DASD file assignment problem. Performance Evalution Review, 17(1):1--10, May 1989.

....of disk accesses. 10] evaluates disk performance with large disk queues (up to 1,000 requests) for various scheduling algorithms. 11] discusses the performance advantages of mirrored disks. 12] proposes to move idle disk heads to the center of the disk to minimize the expected seek delay. [13] proposes an optimal means for balancing disk load over several devices based on the system I O configuration and traces of file activity. Other means of improving disk performance include reducing the fraction of disk space used on devices to reduce the average load on the device, and restricting ....

J. Wolf, "The placement optimization program: a practical solution to the DASD file assignment problem," technical report, I.B.M. Thomas J. Watson Research Center, 1987.

.... storage can be found in [Golding95] 1 Our problem is also like the file assignment problem, which makes an assignment of files to disks that optimizes performance of the I O subsystem over some reasonable period of time, while meeting appropriate system and user imposed constraints [Wolf89]. 4 1.3 The complex device problem Storage devices The components of storage systems include file systems, databases, disk device drivers, tertiary storage managers, as well as the storage devices themselves. Most storage systems are composed of a multitude of components. For example, even a ....

Joel Wolf. The placement optimization program: a practical solution to the disk file assignment problem. Proceedings of ACM SIGMETRICS Conference on Measurement and Modeling of Computer Systems (Berkeley, CA). Published as Performance Evaluation Review, 17(1):1-- 10. ACM, May 1989.

.... a large number of disks on the servers and intelligent controllers which utilize multiple heads for reading in parallel from replicated data (Figure 2) We assume that each disk has a copy of the database full replication for it provides a practical approach to the data allocation problem [Wol89] and does not depend on the quality of the allocation and striping methods. This configuration is very similar to RAID level one [PGK88] The job management uses a locking mechanism similar to that of the SCS concurrent servers with the only exception that it uses the read one write all protocol, ....

J. Wolf. The Placement Optimization Program: A Practical Solution to the Disk File Assignment Problem. Performance Evaluation Review, 17(1), May 1989.

....for file allocation, with the simplest one being the roundrobin scheme. A simple but effective heuristic algorithm for static file allocation, where all files are allocated at the same time and the heat of each extent can be estimated in advance, has been introduced in [5] see, for example, [21] for a more sophisticated approach to statically load balanced data placement) The algorithm first sorts all extents by descending heat and the extents are allocated in sort order. For each extent allocation, the algorithm selects the disk with the lowest accumulated heat among the disks which ....

Wolf, J., "The Placement Optimization Program: A Practical Solution to the Disk File Assignment Problem, " Proc. ACM SIGMETRICS Conf., 1989

....realistic algorithms for static allocation of non partitioned files need to consider additional parameters and system constraints such as controller contention and storage space limitation. A comprehensive, heuristic optimization method which considers some of these constrained is presented in [82], where a non linear programming solution embedded in a queueing network model is described. Moreover, in many application environments, the files are not allocated all at the same time, but rather some files are allocated dynamically. For this dynamic case, the following canonical extension of ....

J. Wolf, The Placement Optimization Program: A Practical Solution to the Disk File Assignment Problem, Proceedings of the International Conference on Measurement and Modeling of Computer Systems (ACM SIGMETRICS), 1989, pp. 1--10

....people use their experience and the available information to make an educated guess at how to rearrange the data. For example, in some cases information about the average workload seen by each disk is available. Data from very busy disks are exchanged with data from relatively idle disks [Papy88] [Wolf89] [Buze90] More aggressive schemes will use information about individual data sets and may consider variations in the temperatures when making the placement decisions [McEl88] There are essentially two problems with these algorithms for load balancing. First, they can be quite expensive. ....

....of disk accesses may be necessary to rearrange the data. This final step would need to be scheduled during a period of little or no activity to avoid serious performance degradation. The human effort described in the papers cited above is considerable, and some attempts have been made to reduce it [Wolf89] [Asch89] The second problem is that dynamic data placement rarely succeeds in solving the load imbalance problem. There are two major problems which prevent dynamic data placement from being successful. The first problem is that conventional data placement schemes must deal with atomic data ....

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J. Wolf, "The Placement Optimization Program: A Practical Solution to the Disk File Assignment Problem", SIGMETRICS Proceedings, 1989, pp. 110.

....realistic algorithms for static allocation of non partitioned files need to consider additional parameters and system constraints such as controller contention and storage space limitation. A comprehensive, heuristic optimization method which considers some of these constrained is presented in [82], where a non linear programming solution embedded in a queueing network model is described. Moreover, in many application environments, the files are not allocated all at the same time, but rather some files are allocated dynamically. For this dynamic case, the following canonical extension of ....

J. Wolf, The Placement Optimization Program: A Practical Solution to the Disk File Assignment Problem, Proceedings of the International Conference on Measurement and Modeling of Computer Systems (ACM SIGMETRICS), 1989, pp. 1--10

....26, 27] In principle, the data placement problem can be viewed as a file assignment problem, which has been intensively studied in many variants and is known to be NP hard. Hence, viable solutions must be based on a heuristic approach. In the ample work reported on the file assignment problem [6, 28] such heuristics have been investigated only for the static case, that is, when all files are to be allocated at the same time and the access characteristics of the files are completely known in advance. Also, the issue of I O parallelism in servicing a single request has been disregarded so far. ....

....applications, and scientific applications. ffl It is mostly motivated by the evolving disk array technology; however, it is applicable to all sorts of multi disk architectures. The work on disk load balancing in disk arrays reported in the literature has concentrated on static data placement [4, 28] and on improving the performance due to redundant data [11, 12, 13, 18, 19, 20] Dynamic adaptation of the data allocation to evolving access characteristics with the goal of dynamic disk load balancing has not been addressed so far. The rest of the paper is organized as follows. Section 2 ....

Wolf, J., "The Placement Optimization Program: A Practical Solution to the Disk File Assignment Problem," Proc. ACM SIGMETRICS and Performance'89 International Conference on Measurement and Modeling of Computer Systems, Berkeley, 1989, pp. 1--10.

....such as re loading the database. The key issue at this stage is physical database design (index selection, file placement, etc. A large body of research has been carried out in this area, and there is some work that has resulted in practical tuning tools (e.g. 14] 28] 64] 67] 70] [94]) A major shortcoming of this work is that it does not take into account the performance issues that arise in multi user operation. For example, in making the decision about whether an index should be created or not, even the best optimization models would merely trade off the disk access cost ....

J. Wolf. The Placement Optimization Program: A Practical Solution to the Disk File Assignment Problem. ACM SIGMETRICS International Conference on Measurement and Modeling of Computer Systems, Berkeley (1989).

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J. Wolf, "The Placement Optimization Program: A Practical Solution to the Disk File Assignment Problem", SIGMETRICS '89, ACM, May 1989.

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J. Wolf. The placement optimization program: A practical solution to the disk file assignment problem. In Proceedings of the International Conference on Measurement and Modeling of Computer Systems, 1989.

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J. Wolf, "The Placement Optimization Program: A Practical Solution to the Disk File Assignment Problem", SIGMETRICS '89, ACM, May 1989.

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