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The number of input/output operations (IOPS) of the device must not be less than the IOPS of Axxon One VMS.
Axxon One records the archive in blocks of 4 MB every 10 secondss. However, if the block is not filled in 10 secondss, a smaller fragment of the block will be recorded, which will be added to later.
Archive playback is also performed in blocks (except when reindexing, see Console utility for working with archives (vfs_format.exe)).Below you can see how you can estimate the IOPS for Axxon One VMS.
If the average bitrate per camera is less than ~3.6 Mbps
If the average bitrate per camera exceeds ~3.6 Mbps
IOPS during archive recording
Archive recording includes both data input (recording) and output (reading) operationsIOPS (recording) = 0.29 * N
IOPS (reading) = 0.035 * MIOPS (recording) = 0.065 * M
IOPS (reading) = 0.035 * MIOPS during archive playback
Archive playback includes only output (reading) operationsIOPS (reading) = 0.035 * R * S
IOPS during simultaneous recording and playback
IOPS (recording) = 0.29 * N
IOPS (reading) = 0.035 * M + 0.035 * R * SIOPS (recording) = 0.065 * M
IOPS (reading) = 0.035 * M + 0.035 * R * Swhere
- N is the number of cameras being recorded;
- M is the cumulative bitrate of all cameras being recorded, in Mbps;
- R is the cumulative bitrate of all cameras being played back from the archive at normal speed (1x), in Mbps;
- S is the playback speed.
- If you use RAID storage, specify the write-back policy for recording to cash cache memory.
Storage requirements
The disk subsystem capacity of Axxon One Server must be estimated, taking into account the resolution, the compression algorithm, the frame rate of the recorded video signal, the number of video cameras from which the recording to disk(s) takes place, and other recording parameters. In addition, the size of the system log and metadata databases must be considered.
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See the storage calculations below, taking into account the size of the archive, the size of the database, and the size of the archive of the system logs.
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Rate of recording is the frame rate of recording to the archive, frames per second;
3.51 = (60 sec s in min * 60 min in hour) / (1024 KB in MB) is the factor used for KB/s in MB/h conversion;
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Average frame size of 640х480 resolution is:
Average frame size may vary over a wide range depending on the vendor, the model, and the settings of the camera and video image complexity. |
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To calculate the frame size, you can use the ratio , that when increasing the vertical or horizontal resolution two times, the average frame size will be increased four times (this rule is a relative and can be applied only to some camera models). |
Examples of calculating the capacity of the disk subsystem (without the capacity of the system log and metadata databases) are presented below.
Recording parameters | Calculating results |
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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 |
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T is the estimated duration of system log storage , in days.
Metadata database
The following formulas can be used to determine the required disk size for the metadata database:
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If you have less than 15 GB of free disk space, the metadata database is overwritten - the overwritten—the new data is written over the oldest data.
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When calculating disk subsystem capacity, note that the self-diagnostics service may generate up to 100 MB of data per day.
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