Size of disk subsystem will be calculated on the basis of frame resolution and compression, rate of video signal frames per second, number of cameras recording events to the hard drives and other recording parameters.
Take into account the size of the system log and metadata databases.
Size of archives
Size of disk subsystem can be calculated by formula:
Size of Disk subsystem (Mb) = Time of storing an archive (days) x Cameras number x Rate of recording (fps) x3,51 x Time of guaranteed recording from a camera (h / day) x Average frame size (Kb),
where Time of storing an archive is the required time of storing an archive from one camera, days;
Cameras number is the number of cameras recording to the archive;
Rate of recording is the frame rate of recording to the archive, frames per second;
3,51 = (60 sec in min x 60 min in hour)/(1024 kb in Mb) – is the coefficient used for kb/s-Mb/h conversion,
Time of guaranteed recording from a camera is the number of hours of guaranteed recording from one camera to the archive per day,
Average frame size is the average size of the camera frame, kilobytes.
Note
Average frame size for 640х480 resolution is:
Video codec | Average frame size |
|---|---|
H.264 | from 8 Kb to 17 Kb |
MPEG4 | from 8 Kb to 35 Kb |
MJPEG | from 23 Kb to 60 Kb |
Average frame size may vary over a wide range depending on the vendor, model and settings of the camera and video image complexity
Note
To calculate the frame size one can use the ratio, that while increasing vertical or horizontal resolution two times, the average frame size will be increased four times (this rule is a relative one and can be applied only to some cameras' models)
Examples of calculating a size of disk subsystem (without size of syslog database) are presented below.
Recording parameters | Calculating results |
|---|---|
4 cameras with 25 fps and 640х480 resolution, guaranteed recording of 24 hours per day during one week | H.264: from 500 GB to 1 TB |
16 cameras with 12 fps and 640х480 resolution, guaranteed recording of 12 hours per day during one week | H.264: from 500 GB to 1 TB |
4 cameras with 25 fps and 1280х960 resolution, guaranteed recording of 24 hours per day during one week | H.264: from 2 TB to 4 TB |
Database of the system log
The size of syslog database is to be taken into account when the size of disk subsystem is calculated. Estimated size of syslog database is calculated by formulas:
The capacity of the system log database (low detection activity) = D * T * (0.01 GB / day);
The capacity of the system log database (average detection activity) = D * T * (0.03 GB / day);
The capacity of the system log database (high detection activity) = D * T * (0.12 GB / day);
where D is the total number of detectors created in system,
T is the estimated duration of syslog storage, days.
Object trajectory database
The following formulas can help to determine the required disk size for the trajectory database:
Size of object trajectory database = N×T×(0,5Gb / day)– sufficient disk size;
Size of object trajectory database = N×T×(1Gb / day)– sufficient disk size plus reserve space;
Size of object trajectory database = N×T×(5Gb / day)– sufficient disk size plus a large reserve.
N equals the number of video cameras in the system actively recording metadata; T equals the period of time (number of days) that metadata will be stored. By default, T = 30 days.
If you have less than 5 Gb of free disk space, the Object Tracking DB is overwritten - new data records over the oldest data records.