Before troubleshooting an exacqVision system that is experiencing throttling, it is important to know how the software writes video to the disk.
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Each time PSFPI attempts to open a record stream, the disk volumes are checked for available space. The available space is determined by adding 1GB to the currently used space. The volume with the most space available is selected for storage. For example, Drive E: would be chosen in the following Windows environment:
C: (unused)
D: 98% full
E: 97% full
F: 98% full
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Note that, if all volumes are equally full, the oldest video is deleted to make room for the new video.
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A unique problem arises if changes are made to the system’s available drives. For example, suppose you add a drive in the previous example:
C: (unused)
D: 98% full
E: 97% full
F: 98% full
G: 0% full
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All video is then saved to drive G: until it is 97% full. However, if the system was already taxing the available I/O for drives D:, E:, and F:, it could overtax the new drive and result in throttling.
Additionally, after the new drive fills up, it contains all the video for a large span of time; this means that the video it contains will eventually all be the oldest video, and this problem will recur in an endless loop. Then, if cameras are added to a system at a later date, the system could exceed its available I/O.