HP 3PAR StoreServ 7400 2-node HP 3PAR System Reporter 3.1.0 Software User& - Page 207
Calculating Common Performance Metrics, Table 77 Common Performance Columns
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Table 77 Common Performance Columns (continued) Column whist0 d_whist0 ... whist31 d_whist31 rsize0 d_rsize0 ... rsize15 d_rsize15 wrsize0 d_wsize0 ... wsize15 d_wsize15 Type Comment DOUBLE PRECISION Number of writes in service time bucket number 0. NOT NULL DOUBLE PRECISION Difference between whist0 value from last sample for the same object. NOT NULL ... ... DOUBLE PRECISION Number of writes in service time bucket number 31. NOT NULL DOUBLE PRECISION Difference between whist31 value from last sample for same object. NOT NULL DOUBLE PRECISION Number of reads in IO size bucket number 0 (512 bytes). NOT NULL DOUBLE PRECISION Difference between rsize0 value from last sample for the same object. NOT NULL ... ... DOUBLE PRECISION Number of reads in IO size bucket number 15 (16 MiBytes). NOT NULL DOUBLE PRECISION Difference between rsize15 value from last sample for same object. NOT NULL DOUBLE PRECISION Number of writes in IO size bucket number 0 (512 bytes). NOT NULL DOUBLE PRECISION Difference between wsize0 value from last sample for the same object. NOT NULL ... ... DOUBLE PRECISION Number of writes in IO size bucket number 16 (16 MiBytest). NOT NULL DOUBLE PRECISION Difference between wsize15 value from last sample for same object. NOT NULL Although in principle it was not necessary to store the difference values (d_rcount for example), since these can be derived from previous samples of the same object, in practice having the difference values stored in the data tables greatly simplifies the queries and improves the performance of the queries. As described in the comment for the begin column in Table 77 (page 205), the differences are only valid when the objects have the same begin time. Calculating Common Performance Metrics Table 78 (page 207) shows SQL expressions that can be used to calculate various performance metrics from the common performance columns for any sample row. Table 78 Common Performance Metrics for a Sample Row Metric Read IOPs/s Write IOPs/s Total IOPs/s Read KBytes/sec SQL Expression CASE WHEN d_now > 0 THEN d_rcount * 1000000.0/d_now ELSE 0 END CASE WHEN d_now > 0 THEN d_wcount * 1000000.0/d_now ELSE 0 END CASE WHEN d_now > 0 THEN (d_rcount + d_wcount) * 1000000.0/d_now ELSE 0 END CASE WHEN d_now > 0 THEN d_rbytes * 1000.0/d_now ELSE 0 END The Sample Data and Inventory Tables 207