# Example of Calculating Log File Size Requirements

A tool (“Catalyst Memory Allocation Tool”) has been included with your installation to help you decide how to allocate the “non-volatile memory” (NVRAM) installed with your Catalyst. This tool will walk you through the steps in properly allocating memory for log file data, user-recorded messages, and varying sizes of configurations.

The formulas for calculating size requirements are as follows:

- With 256 channels being sampled every fifteen minutes, and with downloads every 24 hours.
- Each channel sample requires 12 bytes regardless of its data type.
- 256 active channels x (24 hrs x 4 samples/hr) x 12 bytes/sample = 294,912 bytes required for 24 hours of logging.
- Assuming the high water level percentage is set at 95%, a comfortable allowance might be to let the above amount of data represent 90% of the File size. Therefore the File size should be 294,912 divided by 0.9 = 328,000 bytes.

The above calculation disregards the amount of "overhead" storage required for each sample interval (typically 32 bytes) as well as the possible logging of alarms, configuration changes, and channel state changes, which occur but can be excluded.

If data sampling is not being used, or if it is being used with substantially fewer channels or longer sampling intervals, then the contributions of the other event categories may no longer be negligible, and in general will be unpredictable. However in that case, one can still allocate substantially more storage space than calculations indicate, since even 256 Kbytes does not have a major impact upon the much larger amount of storage still available for user recorded speech.

The specific impact of log file size upon available speech recording time is to decrease recording time by the following amounts:

- At 1800 bytes/second recording rate: 0.0092 x File size in Kbytes
- At 3600 bytes/second recording rate: 0.0046 x File size in Kbytes

Example:

For a recording rate setting of 1800 and a File size of 256 Kbytes, the reduction is 256 x .0092, or 2.36 minutes.

Note: For more information on available speech recording time, please see Verifying Available Recording Time.