1. The speed of the hard disk Rotationl Speed
That is the speed of the spindle of the hard disk motor. The speed is one of the key factors that determine the internal transmission rate of the hard disk, and it also greatly affects the speed of the hard disk. At the same time, the speed of rotation is also one of the important signs that distinguish the hard disk level. Currently, the common hard disks on the market are generally 5400rpm (rpm per minute) or 7200rpm, and high-end SCSI hard disks can also reach 10000rpm or even 15000rpm. In theory, the faster the rotation, the better.
As the capacity of the hard disk continues to increase, the speed of the hard disk is also increasing. However, the increase in rotation speed also brings a series of negative effects such as increased wear, increased temperature, and increased noise. Therefore, liquid bearing motors (Fluid Dynamic Bearing Motors) used in the precision machinery industry were introduced into hard disk technology to effectively absorb vibration, reduce wear and improve life.
2. Average Seek Time
It refers to the time it takes for the hard disk to move the read and write head on the disk to the specified track to find the corresponding target data. It describes the ability of the hard disk to read data in milliseconds. When the capacity of a single disc increases, the seek action and movement distance of the magnetic head decrease, thereby reducing the average seek time and speeding up the hard disk. At present, the average search time for mainstream hard drives on the market is generally around 9ms.
3. Average Latency Time
It refers to the time when the magnetic head moves to the track where the data is located, and then waits for the desired data block to continue to rotate under the magnetic head, generally between 2ms and 6ms.
4. Average Access Time (Average Access Time)
Refers to the average time when the head finds the specified data, usually the sum of the average seek time and the average latency time. The average access time best represents the time it takes for the hard disk to find a certain data. The shorter the average access time, the better, generally between 11ms and 18ms. Note: Most of the average access time mentioned in many hard drive advertisements are replaced by the average search time.
5. Burst Data Transfer Rate
It refers to the maximum rate of data read by a computer from the internal cache area of the hard disk through the data bus, also known as the external data transmission rate (External Data Transfer Rate). This parameter should theoretically be equal to the speed of the interface. For example, the hard disk of UDMA/66 should be 66MB/s, and the hard disk of UDMA/100 should be 100MB/s. But in fact, due to the problem of interface efficiency, this value is often more than 10% lower than the theoretical value.
6. Maximum internal data transmission rate (Internal Data Transfer Rate)
It refers to the maximum data transmission rate between the head and the hard disk cache, which generally depends on the disk speed and disk data line density of the hard disk. Currently, the internal transmission rate of most hard disks is around 40MB/s, but the maximum internal data transmission rate of a few hard disks has exceeded 50MB/s. Since the internal data transmission rate is the real bottleneck of the system, everyone should distinguish these two concepts when purchasing. However, generally speaking, when the speed of the hard disk is the same, the internal transmission rate with a large single disk capacity is high; when the capacity of the single disk is the same, the internal transmission rate of the hard disk with a high speed is high.
That is the speed of the spindle of the hard disk motor. The speed is one of the key factors that determine the internal transmission rate of the hard disk, and it also greatly affects the speed of the hard disk. At the same time, the speed of rotation is also one of the important signs that distinguish the hard disk level. Currently, the common hard disks on the market are generally 5400rpm (rpm per minute) or 7200rpm, and high-end SCSI hard disks can also reach 10000rpm or even 15000rpm. In theory, the faster the rotation, the better.
As the capacity of the hard disk continues to increase, the speed of the hard disk is also increasing. However, the increase in rotation speed also brings a series of negative effects such as increased wear, increased temperature, and increased noise. Therefore, liquid bearing motors (Fluid Dynamic Bearing Motors) used in the precision machinery industry were introduced into hard disk technology to effectively absorb vibration, reduce wear and improve life.
2. Average Seek Time
It refers to the time it takes for the hard disk to move the read and write head on the disk to the specified track to find the corresponding target data. It describes the ability of the hard disk to read data in milliseconds. When the capacity of a single disc increases, the seek action and movement distance of the magnetic head decrease, thereby reducing the average seek time and speeding up the hard disk. At present, the average search time for mainstream hard drives on the market is generally around 9ms.
3. Average Latency Time
It refers to the time when the magnetic head moves to the track where the data is located, and then waits for the desired data block to continue to rotate under the magnetic head, generally between 2ms and 6ms.
4. Average Access Time (Average Access Time)
Refers to the average time when the head finds the specified data, usually the sum of the average seek time and the average latency time. The average access time best represents the time it takes for the hard disk to find a certain data. The shorter the average access time, the better, generally between 11ms and 18ms. Note: Most of the average access time mentioned in many hard drive advertisements are replaced by the average search time.
5. Burst Data Transfer Rate
It refers to the maximum rate of data read by a computer from the internal cache area of the hard disk through the data bus, also known as the external data transmission rate (External Data Transfer Rate). This parameter should theoretically be equal to the speed of the interface. For example, the hard disk of UDMA/66 should be 66MB/s, and the hard disk of UDMA/100 should be 100MB/s. But in fact, due to the problem of interface efficiency, this value is often more than 10% lower than the theoretical value.
6. Maximum internal data transmission rate (Internal Data Transfer Rate)
It refers to the maximum data transmission rate between the head and the hard disk cache, which generally depends on the disk speed and disk data line density of the hard disk. Currently, the internal transmission rate of most hard disks is around 40MB/s, but the maximum internal data transmission rate of a few hard disks has exceeded 50MB/s. Since the internal data transmission rate is the real bottleneck of the system, everyone should distinguish these two concepts when purchasing. However, generally speaking, when the speed of the hard disk is the same, the internal transmission rate with a large single disk capacity is high; when the capacity of the single disk is the same, the internal transmission rate of the hard disk with a high speed is high.