Hard Disk Requirements and Solutions
There are a number of factors to consider when calculating storage needs. They ff factors are:
- number of cameras
- number of hours per day the camera(s) will be recording
- length of storage (how long the data must be stored)
- type of recording (motion detection, event/sensor-triggered, scheduled or continuous)
- other parameters such as frame rate, resolution and compression
Calculating your hard disk requirements on a DVR using MPEG-4 compression:
In MPEG-4, the images are received in a continuous data stream. It is the bit rate which determines the corresponding storage requirements. The bit rate is a result of a specific frame rate, resolution and compression, as well as the level of motion.
Hardware MPEG-4 compression has an approximate file size from 1-12Kb per frame (CIF) 360x240. Neugent's DVRs have about .5-8.5Kb per frame, depending on video quality settings.
Let's say you have 4 cameras and you need to continuously record video at real-time 30fps at 360x240 resolution. How much hard disk do you need for one month of continuous recording?
Calculation: 5 x F (frame rate) x 60 (sec) x 60 (min) x C (number of cameras)
Ex: 5Kb x 30fps = 150Kbps = 9,000 Kb per min = 540Mb per hour
540Mb x 4 (number of cameras) = 2,160Mb x 24 (hours) = 51,840Mb in one day
In one month, you would need 1,555,200Mb or 1,555Gb of hard disk space |
Linux PC-based LX8000 DVRs
Storage Requirements in GB, Continuous Recording for High Quality 30fps CIF (assumes high motion video) |
Retention Period (in weeks) |
Cameras |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
1 |
79 |
159 |
238 |
317 |
396 |
476 |
555 |
634 |
2 |
159 |
317 |
476 |
634 |
793 |
951 |
1,110 |
1,268 |
3 |
238 |
476 |
713 |
951 |
1,189 |
1,427 |
1,665 |
1,903 |
4 |
317 |
634 |
951 |
1,268 |
1,585 |
1,903 |
2,220 |
2,537 |
5 |
396 |
793 |
1,189 |
1,585 |
1,982 |
2,378 |
2,775 |
3,171 |
6 |
476 |
951 |
1,427 |
1,903 |
2,378 |
2,854 |
3,329 |
3,805 |
7 |
555 |
1,110 |
1,665 |
2,220 |
2,775 |
3,329 |
3,884 |
4,439 |
8 |
634 |
1,268 |
1,903 |
2,537 |
3,171 |
3,805 |
4,439 |
5,073 |
9 |
713 |
1,427 |
2,140 |
2,854 |
3,567 |
4,281 |
4,994 |
5,708 |
10 |
793 |
1,585 |
2,378 |
3,171 |
3,964 |
4,756 |
5,549 |
6,342 |
11 |
872 |
1,744 |
2,616 |
3,488 |
4,360 |
5,232 |
6,104 |
6,976 |
12 |
951 |
1,903 |
2,854 |
3,805 |
4,756 |
5,708 |
6,659 |
7,610 |
Linux PC-based LX8000 DVRs
Storage Requirements in GB, Continuous Recording for High Quality 30fps 1/2 D1 (assumes high motion video) |
Retention Period (in weeks) |
Cameras |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
1 |
159 |
317 |
476 |
634 |
793 |
951 |
1,110 |
1,268 |
2 |
317 |
634 |
951 |
1,268 |
1,585 |
1,903 |
2,220 |
2,537 |
3 |
476 |
951 |
1,427 |
1,903 |
2,378 |
2,854 |
3,329 |
3,805 |
4 |
634 |
1,268 |
1,903 |
2,537 |
3,171 |
3,805 |
4,439 |
5,073 |
5 |
793 |
1,585 |
2,378 |
3,171 |
3,964 |
4,756 |
5,549 |
6,342 |
6 |
951 |
1,903 |
2,854 |
3,805 |
4,756 |
5,708 |
6,659 |
7,610 |
7 |
1,110 |
2,220 |
3,329 |
4,439 |
5,549 |
6,659 |
7,769 |
8,879 |
8 |
1,268 |
2,537 |
3,805 |
5,073 |
6,342 |
7,610 |
8,879 |
10,147 |
9 |
1,427 |
2,854 |
4,281 |
5,708 |
7,135 |
8,561 |
9,988 |
11,415 |
10 |
1,585 |
3,171 |
4,756 |
6,342 |
7,927 |
9,513 |
11,098 |
12,684 |
11 |
1,744 |
3,488 |
5,232 |
6,976 |
8,720 |
10,464 |
12,208 |
13,952 |
12 |
1,903 |
3,805 |
5,708 |
7,610 |
9,513 |
11,415 |
13,318 |
15,220 |
What are the types of DVR storage solutions?
When you buy a DVR, you would also need to choose the right type of storage solution. There are two ways to approach hard disk storage: one is to have the storage attached to the actual DVR server. The second option is to obtain a detached storage solution where the storage is separate from the digital video recorder.
Direct Attached Storage
One of the most common solutions for hard disk storage in small to medium-sized installations is direct attached storage. The hard disk is located in the digital video recorder system. Space availability is determined by the PC and the number of hard disks it can hold. Most PCs can hold 2 disks and some up to 4 disks, with each disk containing approximately 300Gb. With this storage solution, you can have a total hard disk capacity of approximately 1.2Tb (Terabyte).
Detached Storage: Network Attached Storage (NAS) and Storage Area Network (SAN)
Some cases where the amount of stored data and management requirements go beyond the limitations of direct attached storage, a separate storage system is implemented. These are Network Attached Storage (NAS) and Storage Area Network (SAN).
Network Attached Storage
This storage system provides a single storage device which is directly attached to a local area network and offers shared storage to all clients on the network. It is simple to install and very easy to administer, providing a low-cost solution for storage requirements, but limited throughput for incoming data.
Storage Area Network
This is a high speed, flexible and centralized network storage system, connected to one or more digital video recorder systems via fiber. Users can access any of the storage devices on the SAN through the digital video recorder systems, and the storage is scalable to over hundreds of terabytes. Just imagine how much data you can store!
The difference between the two is that NAS is a storage device where data is stored on one single hard disk, whereas SAN consists of a number of storage devices where data can be stored block by block on multiple hard disks. This offers a larger and scalable hard disk space, where large amounts of data can be stored with a high level of redundancy.
What is RAID?
RAID or Redundant Array of Independent Disks is a way of arranging standard, off-the-shelf hard drives so that the operating system sees them as one large logical hard disk.
Listed below are the most common levels of RAID with corresponding level of redundancy. Redundancy levels range from practically zero redundancy to a full "hot swappable" mirrored solution where there is no disruption to the operation of the DVR system and no lost data in the event of hard disk failure.
Raid Level |
Characteristics |
Raid - 0 |
Data is being divided over two or more hard disks, for improved read/write speed but no redundancy. |
Raid - 1 |
Raid-1 level or disk mirroring uses at least two disks of duplicate data. There's no division of data and both disks can be read at the same time. |
Raid - 5 |
Raid-5 includes a rotating parity array, allowing all read and write operations to be overlapped. Raid-5 stores parity information for reconstruction of any lost data. It requires at least 3, and runs with up to 16 disks in the array. |
How can you save storage space with Neugent's Linux DVRs?
You can save a lot of storage space with the our Linux DVRs simply by choosing the right formula when recording. For instance, you can adjust the recording function to record at real-time 30fps (per channel) only when there is an event or an alarm is triggered, but normally it just records -- say at 5 fps (per channel). You can also set schedules, to maximize your storage space. You may also choose from a variety of video quality and resolution settings.
Contact us
Neugent Technologies, Inc.
Topy Building I
#3 Economia Street, Bgy. Bagumbayan,
Libis, Quezon City
Call : +632-706-4541 ; 1-714-684-8116
Email us at info@neugent.net for your inquiries.
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