Official WLANmall Blog

Storage is a big part of IP video security and so I thought I would start a small series of video storage starting with the basics. Today we will discuss RAID. RAID has been discussed many (x4) times throughout the years but I still get questions about it. What is it, what is the best choice for RAID for my VMS, etc. So here we go.

There are 4 major types of RAID 0, 1, 5 & 6. There are then combinations of two of the above like RAID 10, 50 & 60. We will discuss each briefly.

JBOD:
JBOD stands for “Just a Bunch Of Disks” and basically means that NO RAID has been implemented.  This is how disks begin and you will then implement RAID on a JBOD storage array.

RAID 0:
RAID 0 stripes data across multiple disks WITHOUT parity.  Allowing you to combine the storage capacity of multiple disks by writing small pieces of it across multiple hard drives.  RAID 0 however provides no data protection.  If one of the disks in the RAID 0 array fails you will lose data on ALL disks.

Tip: You can estimate a RAID 0 array’s usable capacity by this simple equation, R *n = U.  Where R is the raw capacity of one hard drive, n is the number of hard drives in the array and U is the usable capacity of the array.

For the full blog post including descriptions and diagrams of each RAID level please visit Security Info Watch: The Command Line Blog

It has been brought to my attention that I forgot to mention how to fix the problem of weak client side transmission, which I discussed back on August 18th. So I figured I would quickly fill in that void.

There are several ways to increase the range of your wireless client and each has its own benefits and drawbacks. Now, while you read this entry please remember that, like a standard wireless access point or bridge, there are always two parts to a wireless client, the “radio” and the “antenna“. The radio is the device creating the RF signal and the antenna amplifies that signal.

So that being said I am sure you can guess that the first way to increase the range of yourwireless client is…Add an antenna!

1) Add an antenna to your client device. In mobile applications you would want anomnidirectional antenna (signal is radiated in a 360 degree pattern) and for fixed environment you would be better served by a directional panel antenna or grid antenna (signal is more focused in a certain direction). Of course you need to have a client device (PC card or laptop card) that has an external antenna connector built in. The major issue is that most (99%) of laptops have integrated wireless cards and antennas that can not be upgraded in which case you might better be served by number 2 below.

2) The next step is to add a wireless card into your laptop or desktop that has the necessary external antenna connector and then add a high gain external antenna to really boost the signal. This is a pretty easy way to increase wireless transmission and is great for laptops however not so great for desktops. If you want to use this method to increase your wireless signal on your desktop you will normally be required to run a good amount of coaxial cable from the PC up and out to the external antenna. This is definitely the method of choice for laptops but I find it a little cumbersome for desktop machines. Below you can find a picture of cards with external antenna connectors.
The one of the left is made by Ubiquiti Networks and goes in the PCMCIA card slot on the side of your laptop. The one on the right is a PCI card for your PC. You can remove the rubber duck antenna that comes with the card and install coax cable that runs to the antenna you installed on your roof.

3) The third option is great for fixed environments like homes, RVs, boats, etc. Purchase anexternal wireless client that sits on the roof of whatever structure you are in. This client can be an all in one device with both the radio and the antenna built in to one unit or you can purchase one with an external connector for higher gain antennas. Here is what they look like…
Here is how you would use them…

Option 1: Install the external wireless client on your roof, point it at your ISP, run an Ethernet cable from the client to the power over Ethernet injector and then plug it in directly to you PC.

Option 2: Install the wireless client just like in option one but instead of plugging directly into your PC plug it into a wireless router! This will allow you to rebroadcast the signal from outside wireless INSIDE your house, giving you the best of both worlds!

Hope this helps!

1. Decide the number of cameras you need for your installation
2. Choose the codec or combination of codecs, frame rate, resolution and the estimated recording time for each camera.
   • Codecs: MJPEG, MPEG4, MXPEG, H.264
   • Frame rate: Up to 30 fps. From experience you will see that 4-6 frames per second will be sufficient in most security applications.
   • Resolution: CIF (320×280), 4CIF (640×480), 1.3MP (1280×1024), 2MP (1600×1200), 3.1MP (2048×1536), 5MP (2560×1920)
3. Use calculators to estimate amount of storage and server requirements.
   • MJPEG Storage Calculator
   • MPEG4 Storage Calculator
   • Server estimator
   • Lens Calculator
4. Order your server and configure the server according to calculated specifications. Below you will find some best practices. Please refer to the image below while reading this section.
   • Live database should be written to fast reliable SCSI or SAS hard drives.
   • Create a RAID1 logical drive using 2 physical SCSI or SAS disks. Then…
     • Carve out a 20GB or so partition for the operating system (C: drive) and then partition the rest for the live database (D: drive).
     • Depending on the number of cameras in your system you may not have enough capacity for the entire live database on the D: drive so extra disks will be required. These extra disks should be configured as individual RAID0 virtual disks in your RAID controller.
       • The RAID0 is important because it speeds up the write time which is critical in IP video where data is constantly being written to the media.



5. Setup physical archive storage. Your archive storage should be protected from loss so a RAID5 configuration is a good choice. In a small system you can use internal disks but in larger systems you will need either an external disk array, a NAS or a SAN. (see the figure above)
6. Install Milestone on C: drive
7. Through the Admin, install the DLKs provided to you by your Milestone Certified Partnerand add all the cameras to XProtect.
8. Set up camera parameters. With the recording server stopped go through each and every cameras configuration and recording, event and motion attributes. Be sure to set each camera’s live database directory to the appropriate disk. Please refer to step 4 and the image below.



9. Set up camera archive parameters. Go through and set up each cameras archive schedule and directory.



10. In the Image Server Administrator, set up users (basic or active directory) and give them access to view specific cameras on the Milestone XProtect system.

That’s it!

PLEASE CLICK ON THE IMAGE TO ENLARGE

You will notice that I did not specify any gains on the antenna as every installation is different but in the 2.4 GHz range I find that the 9 dbi omni antenna with 7 degrees on downtilt works great.

OK so I know your next question. How much area will this cover??? Well in the world of wi-fi the two most used words are “It Depends“. You’ll hate to hear’em but you better get used to them as there is never a clear answer. RF signal propagation depends on many factors such as interference, environment, line of site and the most overlooked factor CLIENT TYPE!

Most people understand interference and line of sight but if not you can feel free to read more about it in our growing wireless FAQ, here. However, the one most people do not understand and sometime refuse to understand is that client type can make or break your wireless network. How so? Well…lets take an RV park for instance.

An RV park wants to set up a simple access point in the middle of the grounds to serve its 70 RV users. The client then spends time reviewing access point specs, finds a perfect bridge with a great mix of price and performance. Buys the highest gain antenna he can find and makes sure that there is no excessive loss in the RF cabling. The items arrive via UPS, he sets them up perfectly, similar to the setup shown above and starts walking around with his laptop runningnetstumbler BUT, he is only going a 3rd of the distance he was expecting. This can’t be right he thinks and starts troubleshooting his new hardware. However, what he doesn’t realize is that it has nothing to do with the new access point set up he purchased and everything to do with the low powered wifi card in his laptop.

Communication should always be looked at as a 2 way street. The base station (access point) can be uber powerful and transmit for miles but if the device receiving the signal a mile away can only transmits 300ft the base station will never hear the interesting things the client is saying and communication breaks down. I tried to illustrate this concept and hopefully succeeded but let me know if I blew it.

PLEASE CLICK ON THE IMAGE TO ENLARGE

Bottom line is know your application and build accordingly. Do not focus on one part alone as you will never get the results you are after. Look at your wireless network as a system of components working together to create cohesive communication.