Introduction
In the rapidly evolving world of data storage, the role of storage controllers(memory controllers) has become increasingly vital. Whether you're a tech enthusiast or a business owner, understanding storage controllers is crucial for efficient data management. In this comprehensive guide, we'll delve into the world of storage controllers, exploring what they are, how they work, and why they matter.
What Is a Storage Controller(Memory Controller)?
A storage controller, often referred to as a disk controller, is a crucial hardware component responsible for managing data storage devices, such as hard disk drives (HDDs), solid-state drives (SSDs), and more. It acts as the intermediary between the storage devices and the computer's central processing unit (CPU), facilitating data read and write operations.
The storage controller is an important component in the computer system responsible for data transmission and storage control. The storage controller controls data transfer between the host and the storage device, responds to and manages the host, and is also responsible for tasks such as data verification and fault tolerance.
What is a Storage Controller - Detailed explanation
Working principle of storage controller
The working principle of the storage controller is to connect to the host through the interface and establish a data channel with the storage device. The main tasks of the storage controller include transmitting data, verifying data, and fault-tolerant processing. It encapsulates the data from the host into a specific format and sends it to the storage device through the interface.
 controller working principle diagram.jpg "Memory(Storage) controller working principle diagram")
Memory(Storage) controller working principle diagram
Normally, the working speed of the storage controller is determined by the main control chipset, and the performance of the storage controller is closely related to the speed of the storage device, because the storage controller needs to match the data transmitted from the host to the speed of the storage device. Otherwise, errors or freezes may occur during data transmission. In addition, the storage controller can compress and decompress data as needed.
Regardless of type, memory controllers tend to work the same way. At a basic level, a memory controller serves as the interface between the memory module and the rest of the computer system.
They are responsible for handling memory allocation and memory transactions to optimize memory usage and performance.
The role of storage controller
The role of the storage controller is very important. Mainly manifested in the following aspects:
1. Transmit data: The storage controller can transmit data from the host to the storage device and read data from the storage device to achieve two-way flow of data transmission;
2. Verify data: The storage controller can verify the transmitted data to ensure that the transmitted data is correct;
3. Fault-tolerant processing: The storage controller can perform fault-tolerant processing of erroneous data to ensure that data transmission will not be interrupted due to errors, and at the same time, it can correct errors in data transmission;
4. Data compression and decompression: The storage controller can compress and decompress the data that needs to be transmitted to reduce the pressure of data transmission and increase the speed of data transmission.
Storage controller classification
Storage controllers are usually composed together with the main control chipset. Common storage controllers include IDE, SCSI, SATA, NVMe, etc. Next I will detail the different types of storage controllers.
1. Memory controller
The memory controller is a bus circuit controller used to manage and plan the transmission speed from memory to the CPU. It can be a separate chip or integrated into a related large chip;
Such as a microprocessor and The memory controller built into the Northbridge controls the necessary logic to read and write to DRAM, and refreshes the contents of the dynamic random access memory (DRAM) at regular intervals. If DRAM is not constantly refreshed, the written data will be lost, because the storage unit of DRAM is actually a type of capacitor, and the capacitor will continue to leak the charge it stores. According to the JEDEC standard, as long as the leakage speed is not less than 64 milliseconds, the memory can work normally. . When performing read and write operations, the memory controller selects rows and columns according to the data address to the DRAM, and merges the data through a multiplexer to reduce the bus width required for the operation. The multiplexer at the DRAM input terminal The circuitry handles the conversion operation, where the correct memory location is selected for the converted input data via the DRAM's demultiplexer and the data is returned. The bus width is the number of memory cells that allow simultaneous communication. The bus width of memory controllers ranges from 8 bits in early systems, to 512 bits in more complex systems and graphics cards. This is often implemented as several 64-bit memory controllers running simultaneously in parallel, which is called " group model". Some memory controllers, such as the Power QUICC II processor with integrated QUICC memory controller, can connect to a variety of different types of devices at the same time,
Such as: SDRAM, SRAM, ROM and memory-mapped I/O. Some memory controllers integrate ECC error detection and correction functions. The memory controller in the current experiment not only contains the first level of address translation for performing memory management unit, but also contains the second level of address translation, further reducing bandwidth usage.
2. Hard Disk Controller
The hard disk controller is the disk drive adapter. It is the interface device between the computer and the disk drive. It receives and interprets commands from the computer and sends various control signals to the disk drive. Detect the status of the disk drive, write data to the disk and read data from the disk according to the specified disk data format. There are many types of disk controllers, but their basic composition and working principles are generally the same. It mainly consists of a control logic circuit and a microprocessor connected to the computer system bus to complete the reading and writing of read data separation and write data compensation. Data decoding and encoding circuits, data error detection and correction circuits, logic circuits that control data transmission, serial-to-parallel conversion and formatting according to commands from the computer, read-only memory that stores the basic input and output programs of the disk, and It consists of buffers for data exchange and other parts.
Hard disk controller circuit board picture
3. IDE controller
IDE controllers are often built into motherboards and can support up to 4 hard drives and transfer data up to 66 Megabytes (MB) per second, but many IDE controllers can only reach 33 Megabytes. There are several variations of IDE controllers. The most common one is ATA: Advanced Technology Attachment. ATA is a second controller invented by IBM that is installed in the hard disk and can greatly speed up data transmission. Currently, ATA-3 and ATA-4, which have further improved performance, are being widely used in audio workstations.
IDE storage controller
4. SCSI controller
SCSI is a very advanced hard disk controller, but it is usually more expensive than IDE and therefore difficult to popularize. SCSI can support multiple hard drives, CD-ROMs, scanners and other devices, and can connect up to 30 devices and peripherals in a daisy chain. It is most suitable for recording studios that require huge capacity. SCSI controllers are traditionally faster than IDEs, capable of reaching speeds of 160MB per second, and new controllers are being developed that can even reach 320MB per second. Just like IDE, SCSI has a few different versions. If your DAW(Digital audio workstation) requires the best performance, uses the 24bit/96Khz or 24bit/192KHz specification standard, and stores large amounts of data, SCSI should be considered first.
SCSI Controller Card
5. MVMe controller
NVM Express (NVMe), or Non-Volatile Memory Host Controller Interface Specification, is a logical device interface specification. It is a bus transmission protocol specification based on the device logical interface (equivalent to the application layer in the communication protocol) similar to AHCI. It is used to access non-volatile memory media (such as flash memory) attached through the PCI Express (PCIe) bus. solid state drive, although in theory the PCIe bus protocol is not necessarily required.
PCIe 4.0 NVMe SSD Controller
NVM stands for the acronym for non-volatile memory, a common form of flash memory used in solid-state drives (SSDs). This specification mainly provides a low-latency, internal concurrency native interface specification for flash memory-based storage devices. It also provides native storage concurrency support for modern CPUs, computer platforms and related applications, so that host hardware and software can make full use of it. Parallel storage capabilities of solid-state storage devices. Compared with AHCI in the previous mechanical hard disk drive (HDD) era, NVMe/NVMHCI reduces I/O operation waiting time, increases the number of operations at the same time, and has a larger capacity operation queue.
Relying on the PCIe bus, NVMe devices can be applied to various physical slots that support the PCIe bus, including standard-size PCIe expansion cards (usually 4 PCIe channels) and U.2 physical connection interfaces (SFF-8639). 2.5-inch/3.5-inch standard size SSD drives, SATA Express bus (PCIe compatible) devices, M.2 specification expansion cards, etc.
6. Disk array controller
The array controller is used for disk arrays and is the brain of the disk array. The hardware consists of CPU, cache (Cache) and fiber channel (FC). It is mainly used to store and forward data and manage the entire array. It is the system host and storage device. (disk cabinets).
Disk Array Controller
The specific functions are:
Control and decode the instruction flow, including execution of scalar operation instructions.
Send control signals to pe when performing vector operations.
Broadcast the common address part to all processing units.
All processing units broadcast common data.
Receive and handle trap or interrupt signals.
Code sample for storage controller
// Code sample for storage controller
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// data verification function
int check_data(char *data) {
int sum = 0;
for(int i = 0; i < strlen(data); i++) {
sum += (int)data[i];
}
return sum;
}
// data compression function
void compress_data(char *data, int size) {
for(int i = 0; i < size; i++) {
if(data[i] == data[i+1]) {
data[i+1] = 0;
}
}
}
// data transfer function
void transfer_data(char *data, int size) {
printf("data transfer in progress...\n");
// 数据传输操作
printf("data transfer completed！\n");
}
int main() {
char data[] = "Hello, world!";
int check_sum = check_data(data);
printf("the checksum of the data is：%d\n", check_sum);
compress_data(data, strlen(data));
printf("the compressed data is：%s\n", data);
transfer_data(data, strlen(data));
return 0;
}Conclusion
In today's data-driven world, storage controllers play a pivotal role in ensuring efficient data management, protection, and accessibility. Understanding their functions and types is essential for making informed decisions when setting up or upgrading your storage infrastructure. Whether you're a home user or managing a large enterprise, the right storage controller can make all the difference in your data storage experience.
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