Live Video Is Choppy, Tech Says It Is Because System Is Backing Up

Hi, i was recently looking at a nightclub IP cctv system. I noticed the live view appeared choppy as if a slightly low frame per second speed, when i would have expected it to be flowing live images. The tech on site said was due to the redundancy back up system saving data to additional hard drives, causing a delay and slightly slow fps appearance. Is this likely? thanks.


"due to the redundancy back up system saving data to additional hard drives, causing a delay and slightly slow fps appearance."

While it is possible, it implies that the recorder was specified with insufficient resources to handle the load of the system. There's no reason a system cannot back up data and display live video at the same time.

Do you know if the frame rate was configured low by the tech or was the system 'losing' live frames?

Whatever it is, it seems to be a poor job.

"due to the redundancy back up system saving data to additional hard drives, causing a delay and slightly slow fps appearance."

If the recorder has only a single network port, and if its already close to maxed out for bandwidth, and if the "redundancy back up" is backing up to something like an external NAS using the same network port, I could see it having issues. This would be a poor design in itself, but as John already said, seems to be a poor job.

In my experience, when one talks about "redundancy" they are talking about RAID 1 (Mirroring) in where the system writes to two drives simultaneously and if one drive fails then the other takes over. As far as I know there is zero performance difference in writing with RAID 1 and ive heard some people say that reading will benefit with increased performance (since it can read from both drives at the same time) though I have never benchmarked this myself to know for sure.

John, wouldnt it be possible to tell the difference between a low frame rate and an overwhelmed system just by looking?

I would think that a low frame rate would be consistant in that you would see the choppyness and it would be consistantly choppy (constant frame rate), where an overwhelmed network I would assume would either drop random frames (if UDP), or come in bursts when bandwidth allows (if TCP) - (eg. still image for a few seconds, then video comes in and plays fast all at once).

I would also assume if it was overwhelmed (either bandwidth or storage) that the streams would possibly become unsynchronized? Although I think I've seen systems unsynchronized in the past without necessarily being overworked. I never really purposely overwhelmed a system to see what it does so maybe you could share your experience on that for me?

In my experience, when one talks about "redundancy" they are talking about RAID 1 (Mirroring) in where the system writes to two drives simultaneously and if one drive fails then the other takes over...

Agreed, the tech is most likely talking about a real or percieved RAID performance penalty, not necessarily doing a backup. Hard to be sure because the tech's language is strange:

redundancy back up system saving data to additional hard drives...

Not to mention the phrase itself is 4X redundant. But Bradley, why don't you think its not just RAID 5 or 6? They are certainly considered redundant and each have different scenarios that are slower than JBOD.

@Undisclosed A, I get the impression that this system or even this 'tech' is not readily available for reinquiry, and that you are just trying to form an reasonable opinion on a state-of-affairs. Therefore I won't bother listing what to do if we had access to more information, unless you ask.

But Bradley, why don't you think its not just RAID 5 or 6? They are certainly considered redundant and each have different scenarios that are slower than JBOD.

Oh it absolutely could be, it could even be RAID 10. I just dont have enough experience with them to comment thats all. Most of the time, I would think that RAID 1 is sufficient. I guess it would also depend on what the recorder supports as well, for some reason I was thinking just a standalone NVR running embedded linux, usually RAID 1 is all they support, but if its a larger PC based system for example, then absolutely theres numerous RAID/Redundancy options which would all differ in performance