HP 3PAR StoreServ 7000 Storage - Manual (Page 207)

Table 77 Common Performance Columns (continued)
Comment Type Column
Number of writes in service time bucket number 0. DOUBLE PRECISION
NOT NULL whist0
Difference between whist0 value from last sample for the same object. DOUBLE PRECISION
NOT NULL d_whist0
... ... ...
Number of writes in service time bucket number 31. DOUBLE PRECISION
NOT NULL whist31
Difference between whist31 value from last sample for same object. DOUBLE PRECISION
NOT NULL d_whist31
Number of reads in IO size bucket number 0 (512 bytes). DOUBLE PRECISION
NOT NULL rsize0
Difference between rsize0 value from last sample for the same object. DOUBLE PRECISION
NOT NULL d_rsize0
... ... ...
Number of reads in IO size bucket number 15 (16 MiBytes). DOUBLE PRECISION
NOT NULL rsize15
Difference between rsize15 value from last sample for same object. DOUBLE PRECISION
NOT NULL d_rsize15
Number of writes in IO size bucket number 0 (512 bytes). DOUBLE PRECISION
NOT NULL wrsize0
Difference between wsize0 value from last sample for the same object. DOUBLE PRECISION
NOT NULL d_wsize0
... ... ...
Number of writes in IO size bucket number 16 (16 MiBytest). DOUBLE PRECISION
NOT NULL wsize15
Difference between wsize15 value from last sample for same object. DOUBLE PRECISION
NOT NULL d_wsize15
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
SQL Expression Metric
CASE WHEN d_now > 0 THEN d_rcount * 1000000.0/d_now ELSE 0 END Read IOPs/s
CASE WHEN d_now > 0 THEN d_wcount * 1000000.0/d_now ELSE 0 END Write IOPs/s
CASE WHEN d_now > 0 THEN (d_rcount + d_wcount) * 1000000.0/d_now
ELSE 0 END
Total IOPs/s
CASE WHEN d_now > 0 THEN d_rbytes * 1000.0/d_now ELSE 0 END Read KBytes/sec
The Sample Data and Inventory Tables 207