Cam Buckle Tie Down Straps is strong enough for all Light to Medium Loads Duty, suitable for outdoor, kayaks straps tie down, SUVs/car roof rack straps, cargo tie-downs, surfboards cam buckle straps, boat cover straps, luggage straps, furniture, trucks straps, trailers, motorcycles straps, bicycle racks straps, canoes straps, rc battery box tie-down straps, sleeping bags straps, mattress straps, etc. It is a very practical helper for your trips and daily life. Car Trailer Straps,Cargo Belt Strap,4 Inch Ratchet Straps,Vehicle Tie Down Straps,Utv Tie Down Straps,Boat Ratchet Straps WINNERLIFTING SAFETY EQUIPMENT CO., LTD. , https://www.cargostrapfactory.com
Why is the hard drive capacity smaller than the actual label? You should have encountered such a situation, obviously bought a 4t hard drive, why the actual storage is only a little more than 3t. We add hard drives mainly to increase the storage space. Is the problem of reduced storage capacity a problem with the quality of the hard disk?
A hard disk is one of the main storage media of a computer and consists of one or more discs made of aluminum or glass. The disc is covered with a ferromagnetic material. The hard disk has a solid state drive (SSD disk, new hard disk), a mechanical hard disk (HDD traditional hard disk), and a hybrid hard disk (HHD is a new hard disk based on a traditional mechanical hard disk). The SSD uses flash granules for storage, the HDD uses magnetic discs for storage, and the hybrid hard disk (HHD: Hybrid Hard Disk) is a hard disk that integrates a magnetic hard disk and flash memory. Most hard drives are fixed hard drives that are permanently sealed to the hard drive. Hard disk capacity involves scaling between decimal and binary algorithms. Among them, the hard disk manufacturer uses a decimal algorithm for the convenience of calculation, and the computer uses a binary algorithm, and conversion calculation is required between them.
Hard disk manufacturer decimal calculation:
3000GB=3000,000MB=3000,000,000KB=3000,000,000,000Byte
Operating system binary calculation:
3000GB=3072,000MB=3,145,728,000KB=3,221,225,472,000Byte
1GB of actual byte (Byte) calculation:
1GB=1024MB*1024KB*1024Byte=1,073,741,824Byte
Then 3000GB actual capacity:
3000,000,000,000 Byte / (1024 MB * 1024 KB * 1024 Byte) = 2793.97 GB
Why the actual capacity of the 3TB hard disk is 2794.39GB, which is because the hard disk manufacturer in the actual production, the disk will have 0.1-1GB more capacity remaining, so it is slightly larger than the actual capacity of 2793.97GB.
Then when 2794.39GB is converted into TB, the partition is occupied by 177MB, and the remaining capacity is divided by 1024GB. After rounding off, the actual capacity is equal to 2.72TB, which is the origin of 2.72TB capacity.
3TB hard drive price is cheap, the business can not afford to sell, but the historical experience has repeatedly told the business, 3TB hard drive is not sold, but after the sale, the customer returns to 2TB hard drive + price difference. Is it that the 3TB hard drive has been reduced in price and the quality has followed? Of course not, the quality of the hard drive is inherited. Perhaps most netizens can't think of this reason - hard disk partitioning.
The merchant revealed that the most customer feedback is the partition problem. The report shows that WinXP users account for 42% and Win7 users account for 44%. Just because WinXP can't fully recognize the capacity of 3TB hard disk; Win7/8 which supports 3TB hard disk also has the characteristics that the operation process is not simple.
Capacity limitation reasons:
Two years ago, the motherboard BIOS defined 512 bytes per sector for the MBR partition, and the disk addressed 32-bit address. The maximum disk capacity that can be accessed is 2.19TB (232*512byte). Windows starts from the MBR, so each MBR is limited to 2.19TB. The remaining 746GB of the 3TB hard drive is recognized as the second hard drive.
Breakthrough capacity limit:
Starting with Vista and Win7, in order to solve the problem of hard disk limitation, the GPT format has been added. GPT is the meaning of GUID Partition Tables, and GUID is the Globally Unique Identifier. The full name of GPT is the global only yi identification partition table.
The GPT partition table uses 8 bytes or 64 bits to store the number of sectors, so it can support up to 264 sectors. Also calculated on a 512-byte capacity per sector, the maximum capacity of each partition can reach 9.4 ZB (that is, 9.4 billion TB). GPT broke the MBR's 2.19TB limit.
Main performance indicators of the hard disk
According to the main performance indicators of the hard disk, the quality of a hard disk can be measured. Therefore, it is necessary to understand the main performance indicators of the hard disk.
1 capacity
The size of the hard disk is the most important technical indicator for measuring a hard disk, and is the most important parameter for users to purchase. The capacity of the hard disk is determined by the number of disks (number of heads), the number of cylinders, and the number of sectors. The calculation formula is: hard disk capacity = number of disks × number of cylinders × number of sectors × 512B. There are often multiple stacked disk slices inside the hard disk. Therefore, the hard disk capacity can also be calculated as follows: hard disk capacity = single disk capacity × number of disks.
The single-disc capacity of the hard disk has a certain influence on the performance of the hard disk. The larger the capacity of the single disk, the higher the density of the hard disk, and the more information the magnetic head can read in the same time. Therefore, in the case of the same total capacity of the hard disk, it is preferred to purchase a hard disk with a small number of disks.
Many users are often confused about the size of the hard drive. Why is the nominal capacity different from the actual size displayed on the computer? This is mainly due to the fact that the conversion unit is not standard or uniform. At present, it is nominally 1MB=1024KB, and it is also nominally 1MB=1000KB, so there is a situation in which the capacity is inconsistent.
2 speed
Rotation Speed ​​has a direct impact on the data transfer rate of the hard disk. The speed is one of the decisive factors of the internal transfer rate of the hard disk, and is also an important indicator to distinguish the hard disk grade. In theory, the faster the speed, the better, because the higher speed can shorten the average seek time of the hard disk and the actual read/write time, which can improve the read/write speed on the hard disk. But everything has two sides. As the speed increases, the heat generated by the hard disk will increase, and its stability will be reduced to some extent. Today's mainstream hard drives are typically 5400 rpm (rev/min), 7200 rpm and 10,000 rpm. The 7200rpm hard drive has become mainstream.
3 cache
Cache is the place where the hard disk exchanges data with the external bus. Simply put, the larger the cache capacity on the hard disk, the better. The large-capacity cache is good for improving the speed of the hard disk. Currently, the hard disk cache capacity on the market is usually 2MB to 8MB.
4 average seek time
Average Seek Time refers to the time in milliseconds (ms) that the hard disk head moves to the track where the data resides. The shorter the average seek time, the faster the hard drive speed. The average seek time is generally between 5ms and 13ms, and hard drives larger than 10ms are not suitable for purchase.
5 hard disk data transfer rate
The data transfer rate (Data Transfer Rate) of the hard disk is also called the throughput rate, which indicates the speed at which the hard disk reads or writes data after the head is positioned.
6 continuous trouble-free time
Mean Time Between Failure (MTBF) is the maximum time, in hours, from the start of the hard drive to the failure. The average hard disk has an MTBF of at least 30,000 hours or 40,000 hours. This indicator is not available in general product advertisements or in the list of common technical characteristics. It can be specifically referred to the company that manufactures the hard drive when needed.