Specifications

8 – Configuring Points
172 R400
Determining Space Requirements for a History Archive
To calculate the space required for a history archive, add up the space
requirements for each history interval to be included in the archive.
To calculate the disk space required for a history interval, you need to know:
• The maximum number of point parameters (P) that can be collected for that
interval.
• The maximum number of samples (N) that can collected for the interval.
The maximum number of point parameters and samples is determined by
the server database size. For details, see Table 8.3, “Default Retention
Periods,” on page 168.
Use the following formula to calculate disk space in bytes:
Space (bytes) = (P + 2)* (N + 2) * 4
Example If 1-minute history can store samples for eight hours for 1000 point parameters,
the size of the history file would be:
(1000 + 2) * (480 + 2) * 4 = 1,931,856 bytes (1.8Mb)
Creating History Archives
History archives are created using the History Archiving display. History Archives
created using the History Archive report are supported for backward
compatibility.
The History Archiving display allows you to:
• Enable history archiving for each history type
• Check the time of the last archive
• Force an archive to be run
Consideration
The History Archiving display does not display last archive times for history
archives run via a history report.
DD
The day that the archive was made (for example, 03 for the 3rd day of the
month, and so on).
HH
The hour that the archive was made (for example, 13 for 1 pm).
RRR
The number of the history archive report that was used to create the archive.
Where Is…
plscpcg.book Page 172 Monday, May 28, 2001 10:11 AM