Buffer File Maximum Size

The maximum size of each buffer file may be adjusted by the MAXFILESIZE parameter. To estimate the value for this parameter, estimate the number of events generated by the interface. For example, a typical process can generate 1500 exception events/day. A typical event uses 23 bytes in the file buffer (a float32 point). The number of kilobytes per day would be

(# tags collected) x (1500 events/day) x (23/1024 KB) = # KB/day

On Windows and on UNIX versions of PI API prior to 1.6.4, the maximum space used for buffered data is limited to MAXFILESIZE. On UNIX versions of PI API 1.6.4 or later, the maximum space used for buffered data is MAXFILESIZE multiplied by MAXFILECOUNT. To avoid potential problems, OSIsoft recommends setting these configuration parameters to ensure that the maximum space used for buffered data does not exceed available disk space. For default values of these parameters, refer to "Configuring Buffering using bufserv".

Note: When MAXFILESIZE is reached for the file buffer, no more events can be saved into the file buffer. This means that all new events will be lost unless the calling application caches them itself. The file buffer is not circular and does not wrap. Further attempts to put data to the PI Server will return an error (Error number: -182 - See Buffering Errors for more detailed information on that error) and the events will not enter the file buffer. The events will be rejected. Events will also be rejected with the -182 error if the maximum space limit on the disk or partition is reached and space for another file of the required size cannot be allocated.

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