Each CDR log file can be broken down into the following parts:
Protobuf overhead - a small amount of type information about contained records.
A header section - a small amount of data written by the CDR RA including version, host, and timestamp information.
Zero or more AVP CDRs - these records will vary in individual size, and usually form the majority of a CDR log.
A footer - this is empty for Sentinel products.
The combined size of the header, footer, and protobuf overhead is normally trivial (<1KB) compared to the size of each finished CDR log file.
Individual CDR records will vary in size based on dynamic content such as hostnames, Sentinel selection key names, SDP content, and other similarly variable character data. As such, it is not possible to provide exact sizing for a given system without examining the CDR logs written while under a test load, but some approximations can be made.
A basic CDR record containing the information normally written by Sentinel will be on the order of 2000-3000 bytes. With this in mind, the following sections provide rough estimates regarding how much storage would be required for specific scenarios.
If Sentinel is configured to write Session CDRs (i.e. not writing Interim CDRs), then each session will write a single CDR on the order of 2000-3000 bytes.