PCIe SSD was first introduced by Fusion-IO and is widely used by Internet companies and data centers in the form of flash cards. Flash cards are generally used as data caches. If you want to integrate more PCIe SSDs into your server, the form of flash cards is limited. Flash cards have the following disadvantages: l Inserted into the PCIe slot of the server board, the number is limited; l Power is supplied through the PCIe slot, and the capacity of the single card is limited. l On the PCIe slot, it is prone to problems caused by poor heat dissipation and downtime. l Cannot be hot swapped. If you find that the PCIe flash card is faulty, you must stop the service, shut down the server, open the chassis, and remove the flash card. This is a very high management cost for data centers with hundreds or thousands of servers. So, as shown, PCIe SSD introduces a new hardware form: SFF-8639, also known as U.2. U.2 PCIe SSDs are similar to traditional disk-based SATA and SAS drives and can be hot swapped directly from the front panel of the server. Figure 1-1 Hot-swap diagram (this figure is based on the Oracle NVMe SSD hot-swap instructions) When the server has a lot of hot-swappable U.2 SSDs, the storage density is greatly improved. More importantly, U.2 SSDs can be used not only as data caches, but also key data. A RAID array is formed by multiple U.2 SSDs. After a U.2 SSD fails, the faulty SSD location can be determined through the front panel display lights and replaced. At the same time, it will not cause the server to stop service or data loss. At present, many server vendors have released servers with many U.2 SSD bays, some are a mixture of a few U.2 SSDs and most SATA HDDs, and some even have 24 pure U.2 SSD bays. Servers equipped with high-density SSDs can significantly reduce the number of traditional servers for data centers, because many enterprise applications do not require high storage capacity. Traditional mechanical hard disk arrays have a large capacity but are wasted. Enterprises have higher requirements on hard disk bandwidth. An SSD array server can support several times more HDD array servers, and power consumption and cooling costs are several times less. At present, rents and land costs are getting higher and higher, and it is very important for many companies such as telecommunications, video websites, and Internet companies to provide services for a large number of users in a limited data center space. Therefore, it can be expected that as the price of flash memory declines year by year, servers equipped with SSD arrays will become more and more widely used. Let's take a look at the technical implementation of PCIe SSD hot plugging. Traditional SATA and SAS hard disks communicate with the host through the HBA, so they are also managed by the HBA. However, the PCIe SSD is directly connected to the CPU's PCIe controller, and hot plugging requires direct management. According to the Memblaze public number, general hot plug PCIe SSD requires several aspects of support: l PCIe SSD: On the one hand, hardware support is required. SSD generates current peaks during the disk insertion process and causes device damage. On the other hand, the controller should be able to automatically detect the dialing operation to avoid data loss due to power loss. l Server backplane PCIe SSD slot: You need to know whether to support U.2 SSD hot swap through the server manufacturer. l Operating system: To determine whether the hot swap is handled by the operating system or the BIOS, you need to consult the server motherboard manufacturer to determine. l PCIe SSD driver: Whether it is the NVMe driver that comes with the Linux kernel or the driver provided by the manufacturer, it needs to do a lot of hot plug stability testing in various environments to avoid system crash caused by driver problems in actual operation. . Type2 To Type2 EV Charging Cable Type2 To Type2 Ev Charging Cable,Ev Charging Cable Type 2,Ev Cables,Car Charging Cable Yangzhou JERI New Energy Co., Ltd. , https://www.jrevcharging.com