History of recording media
Video recording originated from video tape recorders, which used cassette tapes to store videos. Later, storage media gradually evolved into optical discs, hard drives, and SD/TF cards. The capacity is getting bigger and bigger, and the volume is getting smaller and smaller.
In terms of security surveillance video, cassette tapes were used in the early days, and optical discs were later used. Now mechanical hard disk storage video is still the mainstream, although SSDs and TF/SD cards are also used.
The world’s first hard drive was born in 1956, manufactured by IBM, and the model is 350RAMAC. The disc diameter is 24 inches, the number of discs is 50, and the weight is hundreds of kilograms, which is equivalent to the volume of two refrigerators, but its storage capacity is only 5MB.
In 1980, Seagate developed the first home hard drive.
Since the 1970s, the capacity of hard drives has continued to increase, from the earliest tens of megabytes to the current terabyte level. At the same time, the size of the hard disk is constantly shrinking. Until today, we commonly use 2.5/3.5-inch hard disks and some micro hard disks (hard disks below 1.8 inches, including 1.8 inches). Before and after 2011-2012, SSD hard disks began to enter the consumer market, while the development of traditional mechanical hard disks began to stagnate.
HDD for surveillance
Features of surveillance HDD
The design of ordinary PC hard disks is to meet the continuous development trend of PC applications-more reliable system data storage, diverse application support and faster storage response time.
- More reliable system data storage means that under a hard disk (including array) system, the hard disk system can guarantee the reliable and safe storage of multiple system data.
- Diversified application support means that the hard disk can support multiple application environments: PC desktop applications, multimedia applications, games, etc.
- Faster storage response time, write and read response at any time, fragmented operation.
The surveillance HDD is designed to meet the storage requirements of digital hard disk video recorders for system data and digital image information. The biggest feature of the hard disk is that the reliable support for the system data is extremely stable, which is related to the system characteristics of the digital hard disk video recorder. The system of the digital hard disk video recorder is relatively single (multiple systems cannot coexist), and the applications supported in the system are specially customized for video recording management (there is no coexistence of multiple applications). At the same time, the system is built-in, and has nothing to do with the external video storage hard disk. The special hard disk for monitoring can perfectly meet the needs of digital hard disk video recorders for storing and replaying video images in the form of files. The hard disk is optimized for the characteristics of video file writing and playback to ensure the stability and reliability of its functions.
Difference between surveillance HDD and ordinary HDD
- Continuous working time. The design of ordinary PC hard drives is based on 8 hours × 5 days. 8 hours a day, 5 days a week, the hard disk is in the read and write state. It should be noted that the hard disk has two states after power-on: working state and waiting state. The working state is that the hard disk is reading and writing, and the waiting state is that the hard disk is not reading or writing but in the standby state.DVR special hard disk is designed and developed according to the requirements of enterprise-level environment of 24 hours × 7 days. Work continuously 24 hours a day, 7 days a week.Therefore, ordinary PC hard disks are not suitable for continuous reading and writing for a long time. If ordinary PC hard disks are required to continuously read and write for a long time, it will greatly damage the hard disk, causing the hard disk to have various problems such as abnormal sound, reading and writing errors, and work suspension. Eventually damage the hard disk.The digital hard disk video recorder runs uninterruptedly all year round, so the hard disk must be able to work continuously for a long time.
- Maximum current at start. All 3.5-inch hard disks include a motor system, so when the hard disk is powered on, it is similar to the situation when the motor is powered on: a larger startup current will appear at the initial time of power on to complete the hard disk startup. If the external power supply system of the hard disk cannot guarantee sufficient current support when the power is turned on, the hard disk will fail to start, causing the hard disk to be unusable. And if this happens many times, it is easy to cause damage to the hard disk.The starting current of ordinary PC hard disks is generally between 2.8A and 3.2A. The starting current of the monitoring dedicated hard disk is up to 2.0A. The ordinary hard disk will start at full speed when it is powered on, and the instantaneous current may reach 2A, or even higher, up to 2.8A-3.2A, while the monitoring hard disk will accelerate slowly when it starts, and the startup current will be controlled below 2A .Digital hard disk video recorders often use multiple hard disks for data storage. Take the installation of 8 hard disks as an example: ordinary PC hard disk startup current is 2.8A×8=22.4A, and the lowest power consumption is 22.4A×12V=268.8W. The startup current of the monitoring dedicated hard disk is 2.0A×8=16A, and the highest power consumption is 16A×12V=192W. It can be seen that in the case of the same number of hard disks, monitoring dedicated hard disks have lower requirements on the external power supply system.Note: In the case of the above example, if the external power supply system can only guarantee 250W, some hard disks can be recognized when ordinary PC hard disks are used, and some hard disks cannot be recognized, and there is no regularity.
- Operating power consumption and heat dissipation difference. The operating power consumption here refers to the power consumption of the hard disk in the normal read and write state.The operating power consumption of ordinary PC hard disks is generally about 14.5 watts, and the operating power consumption of monitoring dedicated hard disks is generally about 8 watts. The operating power consumption of special hard disks for monitoring is only equivalent to 55% of the power consumption of ordinary PC hard disks. The low operating power consumption is not only important for the power supply system, but also for the heat dissipation of the video equipment. Approximately 75% of the operating power consumption will be converted into heat.Still the above example, in the digital hard disk video recorder, if 8 hard disks are installed, the total operating power consumption of ordinary PC hard disks is 14.5W×8=116W, and the total operating power consumption of monitoring dedicated hard disks is 8W×8=64W. If an ordinary PC hard disk is used, it can be imagined that there is such a high heat source in such a small space of a digital hard disk video recorder, and the heat dissipation requirement of the system is very high. In order to ensure that the hard disk has a reasonable ambient temperature (0～60℃), The hard disk system must be effectively dissipated. With the use of special hard disks for monitoring, the heating situation is much better-the system’s heat dissipation requirements are reduced and the system is more adaptable to the environment.
- Transmission difference. In addition to the transmission mode of the traditional PC hard disk, the special hard disk for monitoring also introduces an updated transmission mode-the uninterrupted transmission mode, the maximum transmission mode is 65MB/S. By introducing the uninterrupted transmission mode, the hard disk’s support for streaming media is more reliable, and the smoothness and stability of the playback of video files while being recorded can be fully realized. This is a feature that other hard drives do not have.
- Head optimization. The monitoring system generally does not have high requirements for the transmission speed of a single hard disk, but it will frequently read and write small amounts of data. Therefore, it is necessary to optimize the structure of the read-write mechanism of the magnetic head according to the read-write characteristics of the monitoring system to extend the life of the magnetic head.
- Mean Time Between Failure(MTBF). The theoretical average fault-free running time of special hard disks for monitoring is much longer than that of ordinary hard disks, and the stability and reliability are higher.
At present, the ordinary mechanical hard disk market is basically divided by the two giants of Seagate Western Digital. Their hard drive product categories are also similar. The main hard drive products include: PC hard drives, PC solid-state hybrid hard drives, NAS hard drives, surveillance hard drives, enterprise-level hard drives, etc., with capacities ranging from 1TB to 16TB. You can check their official website for details.
In addition to traditional mechanical hard drives, solid state drives (SSDs) are gradually occupying the market of traditional mechanical hard drives due to better stability and fast read and write speeds.
In addition to the traditional Sata interface, solid state drives also have SATAe, U.2, mSATA, M.2, PCIe and SAS interface forms.
Main parameters of HDD
- Rotating speed
- Average seek time
- Transmission rate
Common HDD failures and troubleshooting in security monitoring
DVR cannot recognize the hard disk
- The video recorder does not support hot plugging when connected to the hard disk. When the video recorder is powered off, connect the hard disk and then power on to start the video recorder;
- Check whether the hard disk has a normal power supply and whether the sata data cable is properly connected. You can replace the SATA data cable and check whether the power cable of the hard disk is normal.
- It may be a compatibility problem between the hard disk and the device. Try to replace another hard disk. NVR/DVR recommends using a special hard disk for monitoring.
- Check whether the NVR/DVR standard power adapter is used. It may be caused by insufficient power of the power adapter.
- It may be that the hard disk is damaged and cannot be used normally. Connect it to a computer or other video recorder equipment and test whether the hard disk is damaged.
- Restore the recorder to the default configuration, and confirm that the program of the recorder has been updated to the latest version.
Can’t recognize the hard drive, but it’s okay after rebooting?
The hard drive’s motor is about to expire. At this time, you can re-read the hard disk by restarting it. If the hard disk has been used for a relatively long time (for example, 3 years), it may be that the hard disk has been declining, and the hard disk needs to be replaced at this time.
Hard Disk Test Tool
Generally, hard disk manufacturers provide official hard disk detection and testing tools, which can detect the manufacturer’s own hard disks. For example, Seagate’s SeaTools can check the operating status of the hard drive, and Western Digital’s Data Lifeguard Diagnostic can identify, diagnose and repair the hard drive.
At the same time, there are many third-party hard disk detection and repair tools available. Such as HD Tune, Disk Genius, Crystal Disk Info, etc.
Surveillance video hard disk capacity calculation
In the planning of security video surveillance project, how to calculate the hard disk capacity required for recording, please refer to this article-How to calculate the file size of security video. In practical applications, there are many online tools that can be used. You can try IPSECU’s Video capacity Calculator.
In actual applications, through troubleshooting and some of the above-mentioned hard disk detection tools, it is determined that the hard disk has been damaged. How to repair it?
If you don’t need the data in the hard disk, you can try to plug and unplug the hard disk, reconnect to the recording host, see if it can be recognized, and then format. Or connect the hard disk to the computer, format it and repair it, and then reconnect it to the recording host for use.
If you still need the data in the hard disk, you need to find a special data recovery agency to open the disk and repair it.
Generally speaking, hard disk repair has the following steps:
First, open the hard disk in a dust-free working environment, and replace the damaged head or other parts in the hard disk;
Secondly, reassemble the newly replaced parts and the original parts into a hard disk, and debug the corresponding firmware;
Then magnetic field cloning, the complete copy of the information in the damaged hard disk to a new undamaged hard disk, this part is the longest time-consuming in the entire data recovery. Depending on the degree of damage to the disc, it can take from a few hours to a month;
Finally, reorganize the data in the cloned hard disk and extract the rescue data.