Calculating Space Requirements

This section presents an example of using the formulas to estimate the performance database size for a fictitious organization.

Company ABC uses Performance Monitor to monitor two PeopleSoft Applications, Financials and HCM (N=2). Both applications use DB2 Unicode databases. The company has decided that the performance history data will be kept for a 7-day period (D=7). Each system has two web server domains (W=2), two application server domains (P=2), and two PeopleSoft Process Scheduler domains (S=2). The implementation team decides to use the medium application server configuration for both domains. One Master Scheduler exists for each of the systems (MPrcs=1).

It is estimated, on the average, that 10,000 user sessions (L=10000) will be logged per day in each of the systems. During each session, 50 user interactions (clicking buttons, tab to next field or page, and so on) will occur (R=50).

This is the sample calculation for event data space (using the standard formula for a medium configuration):

N x D x [8 x W + 120 x P + 16 x S + 1] x 86400 / A x E

= 2 x 7 x [8 x 2 + 120 x 2 + 16 x 2 + 1] x 86400 / 300 x E

= 1,165,248 rows x 0.9 KB per row

= 1,024 MB

This is the sample calculation for PMU data space:

N x [D + 1] x L x R x M x T

= 2 x [7 + 1] x 10000 x 50 x 9 x T

= 72,000,000 rows x 3.3 KB per row

= 232,032 MB

This is the formula for space requirement for storing performance data on a DB2 Unicode database:

1,024 MB + 232,032 MB = 233,056 MB

Company ABC decides to add a 1 TB disk.

Business is going well for ABC Company. The demand for the Financial application increased by 50 percent. The IT department decided to add new web server, application server, and PeopleSoft Process Scheduler domains for the Financials application (N=1). According to the system administrator, when the application server domain is booted, a “22 processes started” message appears (App=22), and the PeopleSoft Process Scheduler domain shows a “12 processes started” message (Prcs=12). The IT department needs to estimate whether enough disk space is available to store additional performance data.

Use the customized formula to calculate the space requirement for event data that is generated by the new configuration.

N x D x [8 x W + 3 x P x App + 2 x S x Prcs + MPrcs] x 86400 / A x E

= 1 x 7 x [8 x 1 + 3 x 1 x 22 + 2 x 1 x 12] x 86400 / 300 x E

= 153,216 rows x 3.3 KB per row

= 494 MB

System usage increased by 50 percent for the Financials application, so the total space requirement is:

233,056 MB + 494 MB + [233,032 MB/2 x 50%]

= 291,558 MB

The IT department concludes that enough space is available to store the performance data.