~'i:d, ~ ~ COLLECTION AND PRESENTATION OF ON-LINE RESPONSE DATA

Transcription

1 ~'i:d, ~ ~ OLLIO D PIO OF O-LI PO D 'B",(> :]8 om White, Potomac lectric Power ompany B esponse data for on-line I applications is recorded at the transaction level, classified by resource usage and response time, and stored in a data base. ubsequently, management oriented plots are generated with /PH, and PO PLY is used to t::ombine them in reports which draw attention to any non-compliance with specified goals. his poster paper outlines the analysis methodology, discusses the motivation for each type of data display, and provides sample code and /PH output. IODIO he business computer center of the Potomac lectric Power ompany supports I-based applications systems which provide information access in critical areas of company operations. In agreement with application support managers, a methodology for measuring and reporting on response was established. he following elements form the basis of the service level agreement: response goal, given as X % of transactions complete within Y seconds. classification scheme, which divides all transactions into resofce levels. Measurement and reporting inteals. minimum transaction volume threshold, below which the goals are not applied. he determination of agreement with the goals is made during weekly meetings when each manager responsible for an application system reviews the relevant month-to-date response plot Most systems usually meet their goals, so very little time is wasted looking at data which basically says, "everything is OKI" When this is not the case, supporting data can be viewed on additional plots to gain further insight into exceptional conditions. LIFYI IO ll transactions are recorded by he Monitor for I, which collects data in real time and stores it in compressed form. his is read daily by Merrill's MX code and stored in data sets in the MX Performance Data Bas.e. Locally written code then processes the data. he local code works on a subset of the MOIK data set, and uses three predefined formats (figure 1 below) to classify each transaction by its use of I/O, P, and storage resources. If usage of all three resources falls into the first category, the transaction is classified LOW; if anyone resource falls into the second category, the transaction is classified MDIM; similarly, any HIH resource usage will classify the entire transaction as HIH. he resource "filters" are set universally such that over 8% of all transactions are classified LOW, with most of the remaining being MDIM, and about.5%, HIH. hose in the latter category are considered outliers, and are not given a response goal. wo other formats are used to assign a time 1188

2 I' QassifybyP consumption 'I PO FOM BY- saslib; V LB <:pum'.-.2 = 'WW' -1 = 'LOW'.2 <-O.s = 'MDIM' o.s <-HIH = 'HIH'; r Qassify by I/O ount'l POFOMBY=saslib; V LB iocfmt 11-3 = 'MDIM' 31 ~ HIH = 'HIH'; r Oassify by torage High-water Mark 'I POFOMBY=sa&lib; VLBstgfmt - 7OOO = 'WW' 7OOO <.. 1OOOO = 'MDIM' loooo <- HIH = 'HIH'; figure 1 interval, in 1/2 hour increments, and a response level, which can be represented symbolically: {1,2,3,4,5,5 + }. where = 1 means < response < = 1 second =2 means 1 < response < = 2 second =5 + means 5 < response MMIZI O second he subsetted data, which now consist of one observation per transaction, are passed through PO MMY using the interval and response as classification variables (figure 2 below). ach observation in the output data set represents a count of transactions for a given interval, application, resource level, and response level. lso computed is the mean response time for each observation. Finally, a macro supplied by B ystems is invoked to store the data in their IFO/B product's database, from which all graphic reports are derived. POOD=ino;i' ",rt the IFO/Bdata 'I BY c_appl; r by apptication system ID '/ BYeJevJ; r and resource level *' PO MMY WY D=info;j* summarize "'/ BYc.appl; BY c.l\'\; L in.terval JP; ID date; V response; '* calculate the response -, QfPf Of= ibsum M = c_ mean; r mean j figure 2 PI D Incorporated in the method of data presentation are recommendations by idney nehirsh from a paper presented at M '85. 1 In particular, the visual content of the plots presented in the report labeled "IO OMPLD WIHI OL" was designed so that the relevant information needed for a management decision can be obtained in 2-4 cursory glances: (1)Locate the pplication (it's always in the same place on the page). (2)11 the bars are OD BLK: hat's it; verything is OK. (3)HHD (or D on color reports) bar? How close to the 95% goal? lose enough? OK. (4)ot close enough? look at the date. ow there may be something to talk about. By agreement, all empty bars are ignored, as they represent insufficient transaction counts. ll of the text at the bottom of the page can be ignored. because it never changes, excepting the month, which most managers know without searching a report. herefore, the instantaneous management decision can be broken down into just two words: BLK or D, for color reports, or OD or HHD if one is looking at a black & white copy. 1189

3 wo other types of plots are presented to back up the one described above. hese have their own interest, but are not often consulted during the weekly meetings. he first, "M PO', provides an historical picture for those who like to look at averages. he "pplication: LL" plot displays all the applications running in the I address space, except the outliers. he last type, "IO VOLM", shows the distribution of resource levels, as well as the overall transaction rates. It also contains a yardstick" at day, arbitrarily set at 3 transactions, slightly less than 1% of the total. ince there are nine applications, a plot where the ''yardstick' fills the axis represents an application of below average rate. onversely, a short "yardstick" means a relatively high rate. page from each type of report is presented at the end of this paper. OF /PH ach of the three types of plots described above is generated by a separate routine which both retrieves the data from the IFO/B response data set, and plots it into a graphics catalog, using /PH PO H VB ("IO OMPLD WIHI OL" and ''IO VOLM"), and PO PLO PLO ("M PO"). In order to create a single plot in the graphics catalog, for example, the following statements might be used: %LII PPL=MMI; %LlILVL=M; %LIIOL=1; %l O(XP2); By agreement, all goals are specified as 95% completion, which is a constant in the code (XP2 in this example). ote, however, that the actual response level is supplied at invocation time (OL = ) along with a corresponding resource level (LVL = ), thus allowing ease of reporting when changes occur in the service level agreement for any application (PPL = ). Plots are generated, as described above, for all applications, with the output directed into the graphics catalog. In addition, a plot containing annotate text is created one time with PO O. report page is then assembled with PO PLY, specifying a template consisting of six plots overlaid with the annotate text. his is repeated for as many pages as are needed for the report, with all output again directed into another graphics catalog. ach of the three multipage reports is generated, page-by-page, into the final catalog, until all are completed. Finally, a 3- high template is used to create a grid of 8.5 x 11 inch pages on a alcomp 5835 electrostatic plotter, by re-replaying all of the report pages from the catalog into a single plot on the device. his final plot contains up to 54 individual plots, not including the text overlays. he poster used to illustrate this paper is an example of such a plot, and itself contains sample report pages. KOWLDM haren Mingee is responsible for establishing the resource filters used by the classification FOMs. hanks to Mary nn van for providing guidance in using publishing software, and to I hort for keeping the electrostatic piotter rolling. 119

4 F 1. Finehirsh, idney. "ffective ervice Level eporting, M'5 International onference on the performance and valuation of omputer ystems, onference Proceedings, Dallas, December 1985, p.55. and /PH are registered trademarks of Institute Inc., ary,. MX is a registered trademark of Merrill onsultants, Dallas, X. he Monitor for I is a registered trademark of Landmark ystems orporation, pringfield, V. IFOMIO he author may be contacted as follows: om White - oom 222 Potomac lectrlc Power o. 19 Pennsylvania ve., W Washington, D

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