An Overview of Non Volatile Memory Express
NVM Express or Non Volatile Memory Express (NVME) is an interface specification for access to the non-volatile memory on a computer, usually connected through a PCI Express interface. NVMe is a serial bus interface, meaning that it is not designed to be an independent transport layer over other bus types such as SCSI, Fibre Channel, iSCSI, or USB. Rather, it is a bridge between other bus interfaces and standard computer memory. In simple terms, a computer can act as a bridge by using one or more Non Volatile Memory Express devices to access non volatile memory.
It was introduced in the third generation microprocessor environment to replace aged SCSI, FASA, IDE, and USB buses which were unsuited to high-speed access to the host system memory. As part of the revolution, a new architecture was made which supported two independent channels for connecting SCSI and FASA devices. These new channels allowed for single-device implementation and enhanced the performance of existing software. The most significant innovation was the implementation of anti-technology using a PCI-based logical-layer which allowed for faster access to host system memory than with older bus technologies.
Ace has many benefits over other methods. The most important is that it supports both sequential and parallel processes and commands for logical devices. It provides a very high level of compatibility between different operating systems. Additionally, the working group established a number of technical specifications to enable support for new applications and devices while speeding up operation.
As well as supporting parallel execution, ahci has a rich Pointerset interface for programming. The PCVME specification also defines a number of commands which are used to control operations on non-volatile memory devices. The PCVME spec also defines a wide variety of logical Device Interface drivers and commands which can be used to control and use the various stored procedures and functions. The working group has continually worked to enhance the functionality and reliability of the PCVME and other bus controllers to ensure that their backwards compatibility with existing devices is maintained.
A PCI-based logical-Device interface driver is an essential part of the implementation of any act based system. A typical PCI-based logical Device driver will consist of an application programmable interface (APIC), security module, and host function driver. The application programmable interface controls the operations of the logical devices and can be programmed using a VSI or ISA/PCI compliant computer program. The security module controls the integrity of the system and controls access to the non-volatile memory devices. Finally, the host function driver provides the logic required by the PCVME for communication between the APIC and other devices.
Non volatile memory eXchange (NVME) was first introduced in the late 90’s with the intention of replacing the now-obsolete data disk drives. NVME works well with SATA and iSCSI (initiator and target) hard disk controllers. It consists of four major components: an application software driver, storage area device or SLIC, logic devices, and control logic. The logic devices is composed of eight different components including four SCUs and four microcontroller based logic gates. The SCU is generally a PLC based microcontroller that controls the operation of the four different SCUs. The application software driver acts as the software interface to the storage area devices, which are mainly SATA hard disks, Solid State Drives or SSDs, and printed media such as CD-ROMs.
One of the most important features of the new NVME is the support for Universal Serial Bus (USB) and iSCSI. These two technologies provide universal connectivity across different storage media. Another feature that has forced the storage media manufacturers to introduce NVME in their products is the availability of iSCSI command sets. With iSCSI, system administrators can access storage devices from a different location using a local computer without having to use a third party device. Another advantage of introducing NVME into enterprise storage is that it can act as a bridge between various network environments such as PCs, network printers, and other network appliances.
NVME can be used in conjunction with many other technologies such as Fibre Channel (FC), Infrared and iSCSI or built on-board host bus adapters (HBA). With the introduction of NVME-based virtualization solutions, virtualized servers and workstations have been developed. For example, Citrix Xen Server 5.5 with its Microsoft-integrated Resource Guard allows the administrator to manage servers, workstations, and storage without having to understand the underlying infrastructure. This not only increases the convenience of deploying the solution for companies with a limited IT budget, but also reduces maintenance costs, improves scalability, and allows IT managers to take full advantage of NVME technology.