PC selection advice

I am going to help a friend install a CCTV system in his office. My idea is to install a handful of CNB dome cameras and come back to a DVR card installed in a computer.

I am still debating on exactly which camera and DVR card to use, but i also need to source a computer to use.

My first thought was to just grab a cheap desktop PC off Ebay that has an open PCI port, a pretty recent processor and around 4gb ram in it. I am going to be installing an Ubuntu OS and using Zoneminder as the software.

Are there any recommendations to make on PC selection? For instance is there something in particular which will greatly improve the performance?

My thought was to install three 500gb sata drives in a Raid5 since that will help drive speed. Then max out the memory (at least 4gb). Is there anything else which would be beneficial?

Maxing out the memory won't make a big difference - I still have 16-channel Windows-based DVRs out in the field running fine on 512MB (which was huge amounts at the time). It will depend a bit on the exact software, of course, but the biggest user of memory is usually the search database.

RAID5 will also not give a huge performance boost, but it WILL provide better data reliability. With the price of drives today though, I'd probably step up to at least 1TB drives. We've been using (and liking) the Western Digital Caviar Black drives, and the difference between a 500GB and a 1TB is only $30 at our regular retailer. The jump to 2TB is another $90 from there. Don't cheap out on the drives - get the Blacks or equivalent, or better yet, go to enterprise-grade drives, not just for performance, but for longevity. Avoid cheap, 5400rpm, or "green" drives.

Beyond that, even a cheap machine should work fine... but check the recommendations for your card/software of choice, as many recommend only Intel chips and chipsets (no AMD processors, no SiS or nVidia chipsets). Some WILL work fine with others... but many times if the manufacturer says Intel-only, they MEAN Intel-only. Some packages also recommend disabling hyper-threading, so you should check that the motherboard or BIOS supports this.

Let's face it, you're running a simple system. You have no need of running RAID5 to speed things up.

Dependent on how far back you want to go with your recordings. I'd run with a single 1TB or 2TB drive. They're pretty cheap these days.

Western Digital have released a range of surveillance specific drives. I believe they're the EVDS series. Worth a look as they're quite cheap too.

Western Digital have released a range of surveillance specific drives. I believe they're the EVDS series. Worth a look as they're quite cheap too.

You mean these? http://www.wdc.com/en/products/Products.asp?DriveID=615

I made the assumption that disk IO would be high with as much as the system is writing to the disks. In thinking that, I figured a RAID5 would allow the computer to write faster, hopefully shortening the queue length.

With Zoneminder, everything is stored as a .jpg, and if I have 6 cameras recording 24 hours a day at around 10 frames per second, that would be 60 .jpg images being written every second. I assumed that would benefit from more IO.

I did an htop on my computer and saw that the CPU is definitely getting hit pretty hard, so i am going to make sure to get a lot of processing power. Maybe a quad core computer.

Just stay away from the Green drives, the Western Digital AV drives are slower than the Black or Blue drives. Better yet if you have the cash, Solid state is around 260 now, twice the speed of the hard drives. Ofcourse current hard drives are twice the speed of hard drives from a couple years ago. Though in a Geovision system for example, on Windows, I even used an old 5400rpm USB hard drive to test for the video data only and had no issue writing to it, no idea how long term would be though. Geovision creates AVI files, though less files as they are 3-5 minutes long approx, that still takes alot of processing and writing of large files. Running older versions of their software (current versions must be developed on a super computer) they run fine on P4 and even going back a couple years, a celeron 2.8. In the case of Geovision, it likes alot of Memory, using 2Gb in most cases is sufficient, though back in the day, ran as little as 512. In fact an old NetproMax PC DVR I was working on recently had a P4 2.4ghz and only 256MB of memory .. but it was slow and using a newer version of their DVR software, I had to set the recording to CIF as it would crash otherwise! The older software had no major issues with the hardware, but the hard drive had crashed and they no longer had the old software anywhere. They had 2 of them though, the 8 channel with the same hardware was fine using its old software and recorded in 4CIF.

I made the assumption that disk IO would be high with as much as the system is writing to the disks. In thinking that, I figured a RAID5 would allow the computer to write faster, hopefully shortening the queue length.

With Zoneminder, everything is stored as a .jpg, and if I have 6 cameras recording 24 hours a day at around 10 frames per second, that would be 60 .jpg images being written every second. I assumed that would benefit from more IO.

 

I did an htop on my computer and saw that the CPU is definitely getting hit pretty hard, so i am going to make sure to get a lot of processing power. Maybe a quad core computer.

You are not gonna come close to reaching max read/write speeds with 6 cameras.

Thanks for the feedback. I guess over-engineering is better than under-engineering

Thanks for the feedback. I guess over-engineering is better than under-engineering

Understood, but if the over-engineering adds unneeded complexity, it can increase the chances something will go wrong. Sixty CCTV images per second is a very modest bandwidth for one disk drive. You will be able to record and search and playback all at the same time just fine.

Best,

Christopher

RAID5 won't increase your read/write performance anyway, because the controller (software or hardware) still has to maintain the parity information. The point of RAID5 is data integrity/reliability.

RAID5 won't increase your read/write performance anyway, because the controller (software or hardware) still has to maintain the parity information. The point of RAID5 is data integrity/reliability.

RAID5 read performance is almost as good as RAID0, but you're right, RAID5 write performance sucks eggs.

Best,

Christopher