# of cameras and limit writing to 1 hard drive continuously?

[mike_va 0]

Just wondering at what point this starts to become the bottleneck, for continuous writing.

 

I was running 16 cameras, 4 of which were 1.3MP and it seems to hang up on playback somewhat. Running only 8 cameras it seems fine, very snappy and responsive.

 

Still have some processor left as it is a quad core athlon so don't think that is the problem.

 

Thanks in advance.

[thewireguys 3]

What VMS are you using and what is the bandwidth into the NVR?

[Soundy 1]

Depends on the drive as well... "green" drives aren't generally as well-suited for this sort of purpose.

[mike_va 0]

What VMS are you using and what is the bandwidth into the NVR?

It's VitaminD although I'm not sure that qualifies as VMS. It limits recorded frame rate to 10Fps. Someday may change but just so darn easy to review events.

 

Network with the cameras I have on it now is running ~37Mbps, so no more than double that with all of them.

[mike_va 0]

Depends on the drive as well... "green" drives aren't generally as well-suited for this sort of purpose.

Thanks, noted. Would like to understand this so I can know what is limiting the system.

 

The other possibility is the processor, so may try an I7 if it's not the hard drive.

[Soundy 1]

Is this a single-drive system (OS and data on one drive)? How much RAM is in it? Possible if the OS and data are on the same drive, and there's not enough RAM, that pagefile read/write is hampering things.

[Birdman Adam 0]

Yea 'green' drives are horrible for constant recording. Could you tell us what type of drives you have? Brand? RPM? SATA or IDE? Are they in a RAID?

 

Whatever monitor program you use to watch cpu load, see if it can show disk IO. Maybe download a disk speed test like bst to see whether you've got a hidden bottleneck.

 

I just did a quick test and I get 35MB/s write speed to my 7200RPM SATA HD in my laptop - and that is with Truecrypt (the whole drive is encrypted AES). Only uses ~3% CPU to do it. Desktop HD with proper mobo and sata controller will do better!

 

I have my recorded video on separate drives from the OS so that there is no other requests to annoy the disk while its recording.

[thewireguys 3]

Depends on the drive as well... "green" drives aren't generally as well-suited for this sort of purpose.

Thanks, noted. Would like to understand this so I can know what is limiting the system.

 

The other possibility is the processor, so may try an I7 if it's not the hard drive.

 

Processor and memory don't have much to do with recording. I have a dual core atom recording over 100Mb/s stream and it hardly breaks a sweat.

[mike_va 0]

Thanks all, Windows 7 3GB DDR2 ram. Did not know the difference re DDR3 and DDR2 when I bought, seems to be easy to add large amounts of DDR3?

 

OS is on a separate HD, both are SATA. I had to disconnect the DVD drive to hook up the second HD.

 

HDS5C3020ALA Hitachi 6GB/s 2TB, originally bought as a backup drive from newegg.

 

Here's something I found online, if that is really 65MB/s and not bits it seems like that is not the problem?

[mike_va 0]

Processor and memory don't have much to do with recording. I have a dual core atom recording over 100Mb/s stream and it hardly breaks a sweat.

Yes, but the catch is VitaminD does analytics processing to distinguish people vs. objects and takes a fair bit of processor.

 

For example, I can only run 3-4 cameras at 640x480 on an old mac mini core duo 1.66GHz (which is below their recommended processor).

 

I bought the Athlon quad core to overcome this which worked for a while, but I keep adding cameras...

[thewireguys 3]

That's why we do the analytics on the cameras

[mike_va 0]

Whatever monitor program you use to watch cpu load, see if it can show disk IO. Maybe download a disk speed test like bst to see whether you've got a hidden bottleneck.

For example I see it peaking at 5MB/s with 3 cameras at 640x480 on the mac mini. This is what got me to thinking that might be the limitation with the W7 rig, once I add in 4x at 1.3MP and the rest of the cameras maybe this works out to being close to the limit?

 

Not sure how to do this on windows yet but will poke around.

[skane 0]

Depends on the drive as well... "green" drives aren't generally as well-suited for this sort of purpose.

 

+1. I only use Western Digital Blacks, or REs. Got stuttering with others (Seagates including the ES series, WD greens, WD AVs).

 

I leave ~ 15% headroom on the allocations too, if the drive gets too full, things can really slow down.

 

The HD controller (on mobo and add-on card controllers) can matter too...

Edited May 25, 2011 by Guest

[skane 0]

Whatever monitor program you use to watch cpu load, see if it can show disk IO. Maybe download a disk speed test like bst to see whether you've got a hidden bottleneck.

For example I see it peaking at 5MB/s with 3 cameras at 640x480 on the mac mini. This is what got me to thinking that might be the limitation with the W7 rig, once I add in 4x at 1.3MP and the rest of the cameras maybe this works out to being close to the limit?

 

Not sure how to do this on windows yet but will poke around.

 

On Windows 7, you can use builtin resource monitor app.

Leave the monitor window on top while you are browsing archives.

[mike_va 0]

On Windows 7, you can use builtin resource monitor app.

Leave the monitor window on top while you are browsing archives.

Well I was just trying this but it would only show me the drive with the OS...

 

Tomorrow will move everything to C drive and see how it does. Need to sign off for tonight.

[skane 0]

On Windows 7, you can use builtin resource monitor app.

Leave the monitor window on top while you are browsing archives.

Well I was just trying this but it would only show me the drive with the OS...

 

Tomorrow will move everything to C drive and see how it does. Need to sign off for tonight.

 

Any drive with read or write activity will show up under the Disk Activity section when activity occurs.

[mike_va 0]

Well I knew I would not get to sleep without trying this. With 11 cameras (4 at 1.3MP) I get peaks up to 60MB/s. Don't know what the drive is rated for in the computer for the C drive but probably not that great. I can see the lag as it tries to refresh the events view.

 

Not sure how to get around this.

 

Worst case I can add another computer or just keep running it on the ones I have set up.

 

Analytics in the camera is not the way I want to go, but I can see why they do it...

 

I have combination of 3 Axis and one Arecont, and analog cameras hooked up to an Axis 241S rack along with a few other things I am playing with.

 

Kinda funny got back from a trip a few days ago walking through Dulles International Airport they had tons of Arecont. Art Institute in Chicago had various Axis cameras.

[Soundy 1]

Thanks all, Windows 7 3GB DDR2 ram. Did not know the difference re DDR3 and DDR2 when I bought, seems to be easy to add large amounts of DDR3?

You wouldn't really see a difference with large amounts of RAM, and besides, you'd need 64-bit Windows to even see more then 3.5GB of it (you could have 16GB in there and 32-bit Windows will only see up to 3.5GB). As thewireguys says, more RAM wouldn't really help at this point; it's more a matter of whether there's enough that the system isn't swapping to disk excessively.

[Quantum 0]

If you {redacted}

Edited May 26, 2011 by Guest

[Soundy 1]

Read operations are faster on RAID5, but not write operations - don't think that would be a big advantage in this case. RAID0 would be faster, but I really don't like using it for video data - seen too many DVRs lose *all* their data due to a single failed disk.

[thewireguys 3]

Read operations are faster on RAID5, but not write operations - don't think that would be a big advantage in this case. RAID0 would be faster, but I really don't like using it for video data - seen too many DVRs lose *all* their data due to a single failed disk.

 

That is correct and you will need a good RAID card for video.

[Quantum 0]

Read operations are faster on RAID5, but not write operations - don't think that would be a big advantage in this case. RAID0 would be faster, but I really don't like using it for video data - seen too many DVRs lose *all* their data due to a single failed disk.

I guess the rules are different for {redacted}

Edited May 26, 2011 by Guest

[Soundy 1]

Read operations are faster on RAID5, but not write operations - don't think that would be a big advantage in this case. RAID0 would be faster, but I really don't like using it for video data - seen too many DVRs lose *all* their data due to a single failed disk.

I guess the rules are different for Linux.

Not really...

 

http://www.prepressure.com/library/technology/raid

"(RAID5)Advantages

Read data transactions are very fast while write data transaction are somewhat slower (due to the parity that has to be calculated)."

 

I feel sorry for you Windows types.

RAID levels and their relative advantages/disadvantages have nothing at all to do with OS, especially when you're using a hardware controller.

 

A 2TB WD drive from Newegg is $80 these days. Can't lose.

You can, actually... as mentioned previously, some drives don't have sufficient performance or reliability for DVR usage. Rory has mentioned many times the issues he's had with "green" drives on GeoVision systems (stuttering playback, dropped frames, all rectified by switching, even to standard desktop drives). I've found "green" drives generally don't have the longevity of server- or enterprise-grade drives when used in DVRs and RAID arrays, either - remember, this isn't your basic home media server that's seeing maybe a few hours' sporadic access a day; this is something that's seeing sustained read/write for days at a time. Most array manufacturers (QNAP, Synology and Enhance Tech are the ones I've used) list recommended drives for their systems, and none of them recommend green drives for anything but SOHO use.

 

Edit: And yes, RAID10 will give you some benefits as well... at a cost of space. Everything is a trade-off.

[Quantum 0]

Well sure, {redacted}

Edited May 26, 2011 by Guest

[Soundy 1]

Well sure, writing is always slower, and this is made worse by the overhead of RAID5. But writing to RAID is arguably faster than to one drive. I've never used RAID5 and I guess I shouldn't suggest it.

I have, and it works well... if properly implemented.

 

There's a big difference in performance and resiliency between Windows software RAID and Linux mdadm. But I don't care.

Doing RAID in software is a poor place to start anyway.

 

And true, a consumer-grade drive ostensibly is not as dependable as an enterprise-grade drive, but I've never had a WD consumer-grade drive fail on me. And I've never had performance problems with the Green drives. The Mobotix camera at top rez always showed 0% buffer, meaning buffering was never needed using CIFS NAS, and the array was hardly busy. And my home theater computer at home clicks the array (3ea 2TB WD Green BTRFS) about every second when I'm watching an HD movie in MythTV. (completely automatically skipping all commercials, BTW) Not sure how rory's was set up, but WD Greens have never been an issue for me. I'm just sayin'...

 

MythTV is not the same load as a DVR. For one thing, it's not reading *and* writing heavy data streams simultaneously. You're also typically only accessing one, maybe two files at a time (if you're recording one thing and watching another). Remember that a DVR doesn't just have to write to the drive, it also has to keep the files indexed, cataloged in its search database, and keep things cleaned up (deleting old files, etc.). That generally means a lot of constant R/W operations *all over* the volume. And in most cases, that means doing it with the drive(s) heavily fragmented (a few systems pre-allocate large files and then keeps its video in those, but most write multiple smaller files).

 

So no, you can't really compare the performance of a HTPC with that of a surveillance DVR.