PVC High Speed Door are designed for indoor use and ensure rapid handling operations between different areas that should remain separated. These safe and efficient industrial doors are made of a shaped steel frame and covered with PVC. These high speed doors are safe and efficient and consist of a shaped steel frame covered with PVC. Safety is ensured by their photocells and barriers.
High speed doors protect us from harm, save energy and help us to separate processes for optimal productivity. A high speed door's most important job is to simply open and close quickly and safely every time you need it.
The high speed pvc roll shutter door require high strains, caused by the high operating speed and the frequency of openings, have to be taken into account during construction. In the same way, basic conditions like size and installation location add up to considerable requirements regarding safety and control technique.
PVC High Speed Door,Large PVC High Speed Door,Transparent High Speed Door,Great Performance High Speed Door Shenzhen Hongfa Automatic Door Co., Ltd. , https://www.pvchighspeeddoor.com
Disk arrays (Redundant Arrays of Inexpensive Disks, RAID) have the meaning of “a disk array with an inexpensive redundancyâ€. The principle is to use arrays as a disk group to coordinate the design of distributed data to improve data security. The disk array is composed of a number of inexpensive disks, which are combined into a large-capacity disk group. The disk system uses the effect of the addition of data provided by the individual disks to enhance the performance of the entire disk system. With this technology, data is cut into many sections and stored on separate hard disks. The disk array can also use the concept of parity check. When any hard disk fails in an array, the data can still be read. When the data is reconstructed, the data is recalculated and then placed back in the new hard disk. 
classification
There are three types of disk arrays: an external disk array cabinet, an internal disk array card, and a software emulation.
External disk array enclosures are most commonly used on large servers with Hot Swap features, but these products are expensive.
The internal disk array card, because of its low price, requires a relatively high installation technology and is suitable for use by technicians.
Using software emulation, it is not suitable for servers with big data traffic due to the speed of the machine.
advantage
Increase the transmission rate. RAID dramatically increases the throughput of the storage system by storing and reading data on multiple disks at the same time. In RAID, many disk drives can transfer data at the same time, and these disk drives are logically a disk drive, so using RAID can reach a single disk drive several times, tens or even hundreds of times faster. This is the problem that RAID originally wanted to solve. Because the speed of the CPU at that time was growing rapidly, and the data transfer rate of the disk drive could not be significantly increased, there was a need to have a solution to the contradiction between the two. RAID finally succeeded.
Fault tolerance is provided through data verification. Ordinary disk drives cannot provide fault tolerance, if not include CRC (Cyclic Redundancy Check) codes written on disk. RAID fault tolerance is based on the hardware fault tolerance of each disk drive, so it provides greater security. In many RAID modes, there are relatively complete measures for mutual verification/restoration, and even direct mutual image backup, which greatly improves the fault tolerance of the RAID system and improves the system's stability and redundancy. 
Shortcomings
Do different RAID, RAID mode hard disk utilization is low, and expensive.
RAID0 has no redundancy function. If one disk (physical) is damaged, all data cannot be used.
The RAID1 disk can only use up to 50% of the utilization (in the case of using two disks) and is the lowest among all RAID levels.
RAID0+1 is understood to be a compromise between RAID0 and RAID1. RAID0+1 can provide data security for the system, but the protection level is lower than Mirror and disk space utilization is higher than Mirror.
the way
Disk arrays can be implemented in two ways: "software arrays" and "hardware arrays."
The software array refers to the disk management function provided by the network operating system itself to configure multiple hard disks on a connected ordinary SCSI card as logical disks to form an array. The software array can provide data redundancy, but the performance of the disk subsystem will be reduced, and some reductions are still relatively large, reaching about 30%.
Hardware arrays are implemented using dedicated disk array cards. The hardware array can provide functions such as online capacity expansion, dynamic modification of array levels, automatic data recovery, drive roaming, and cache. It provides solutions for performance, data protection, reliability, availability, and manageability. Array card dedicated processing unit to operate, its performance is much higher than conventional non-array hard drives, and more secure and stable.
Disk arrays are actually divided into software RAID and hardware RAID. Soft arrays are created through software programs and provided by the computer's CPU. Since the software program is not a complete system, it can only provide the most basic RAID fault-tolerance functions. Other functions such as the setting of hot-spare hard disks and remote management are all lacking. The hard array is provided by the independent operating hardware to provide the control and calculation functions of the entire disk array without depending on the system's CPU resources. Since the hard array is a complete system, all required functions can be done. So hard arrays provide better functionality and performance than soft arrays; moreover, if you want to implement systems in disk arrays, hard arrays are the only choice. Therefore, we can see that RAID 5 disk arrays in the market are hard arrays, and soft arrays are only applicable to Raid 0 and Raid 1. For our image mirroring tower, we definitely don't use Raid 0 or Raid 1. As a high-performance storage system, it has been used more and more widely. The RAID level has been developed from the RAID concept and has been developed into seven levels. The levels are 0, 1, 2, 3, 4, 5, 6, and so on. However, the most commonly used are 0, 1, 5, and 6 levels.
Introduction