Researching System Administration - Anderson (Correct) ....both reads and writes the mean request rate, request size, queue length and sequentiality, as described in the analysis section. The input queue length and sequentiality are adjusted to take into account the effect of interactions between streams on the same LU using the techniques described in [UAM01] The sequentiality is decreased for two streams that are on simultaneously, because the overlap will cause extra seeks. The queue length is increased because there will be more outstanding I Os, giving the disk array more opportunity for reordering. The utilization of each stream is calculated .... Mustafa Uysal, Guillermo A. Alvarez, and Arif Merchant. A Modular, Analytical Throughput Model for Modern Disk Arrays. In To appear in Proceedings of the 9th International Symposium on Modeling, Analysis and Simulation on Computer and Telecommunications Systems (MASCOTS 2001), Cincinnati, OH, August 2001. -------------------------------------------------------------------------------- ....the workload, summarizes an I O request pattern. Streams capture information about the I O accesses to a single associated store, such as an average request rate, an average request size, and a summary of the sequentiality in block accesses. Further information on stream attributes can be found in [30, 3, 21]. Disks in an array are grouped together into logical units (LUs) using RAID [23] Stores are packed into the LUs of configured disk arrays. The array types available to the design tool are specified as inputs, along with any restrictions on their configuration. Disk arrays inherently have .... [Article contains additional citation context not shown here] M. Uysal, G. A. Alvarez, and A. Merchant. A Modular, Analytical Throughput Model for Modern Disk Arrays. In Proceedings of the 9th International Symposium on Modeling, Analysis and Simulation on Computer and Telecommunications Systems (MASCOTS 2001. -------------------------------------------------------------------------------- M. Uysal, G. A. Alvarez, and A. Merchant. A modular, analytical throughput model for modern disk arrays. In Proc. of the 9th Intl. Symp. on Modeling, Analysis and Simulation on Computer and Telecommunications Systems, pages 183--192, August 2001. -------------------------------------------------------------------------------- ....number of candidate configurations. The performance models have three complementary parts: 1. Inter stream adjustments. The input queue length and sequentiality are first adjusted to take into account the effect of interactions between streams on the same LU using the techniques described in [30]. For example, the sequentiality is decreased for two streams that are on simultaneously, because the overlap will cause extra seeks, while the queue length is increased because there will be more outstanding I Os, which gives the disk array more opportunity for request re ordering to improve .... M. Uysal, G. Alvarez, and A. Merchant. A modular, analytical throughput model for modern disk arrays. In 9th International Symposium on Modeling, Analysis and Simulation on Computer and Telecommunications Systems (MASCOTS -------------------------------------------------------------------------------- ....that workload. In the results reported in this paper, we use our thirdgeneration solver, Ergastulum [5] prior solver generations were called Forum [7] and Minerva [1] Our solvers are constraint based optimization systems that use analytical and interpolation based performance models [3, 7, 18, 23] to determine whether performance constraints are being met by a tentative design. Although such models are less accurate than trace driven simulations, they are much faster, so the solver can rapidly evaluate many potential configurations. As illustrated in Figure 1, the solver designs .... M. Uysal, G. A. Alvarez, and A. Merchant. A modular, analytical throughput model for modern disk arrays. In International Symposium on Modeling, Analysis and Simulation on Computer and Telecommunications Systems (MASCOTS), August 2001. |