Think about NFV! Think about x86 processor ….Both of them are inseparable. Isn’t it?
No matter how simple a processor (compute part) sounds, I bet a lot of people don’t know that the compute domain in NFV is not just the compute processor of the node…Actually it is much more.
The fact is that the “Compute Domain” and the “Compute Node” in NFV does not mean one and the same thing by ETSI definitions. Know it and you will avoid a lot of confusion understanding the NFV basic architecture and avoid misunderstanding while communicating with a vendor/customer on this subject
Of course, you don’t want to go wrong with the basic building foundations of NFV, isn’t it?
And not only that, if you stay until the end, all the essential terminology of servers that you hear every day like COTs, NIC, hardware accelerators would be clarified.
So first of all what is “Compute Domain” versus “Compute Node” in ETSI’s terms?
As shown clearly in the NFV Infrastructure block above, the Compute Domain includes both the compute hardware and the storage hardware. So Compute Domain is the superset, of which the Compute HW/node is just one part.
Surprised, aren’t you? How many of you were thinking of storage as a part of the compute domain?
So let’s go deeper into what is included in the compute domain:
Thee three Parts of Compute Domain
1. Compute Node
In COTS (Common of the shelf) architecture, the compute node includes the multi core processor and chipset which may include the following physical resources
· CPU and chipset (for example x86, ARM etc.)
· Memory subset.
· Optional hardware accelerators ( e.g. co-processor)
· NICs ( Network Interface cards with optional accelerators)
· Storage internal to blade (nonvolatile memory, local disk storage)
· BIOS/Boot loader ( part of execution environment)
A COTS server blade is an example of compute node
2. Network Interface Card (NIC) and I/O Accelerators
As you can see that I mentioned NIC as part of the compute node in earlier section. Which is true. Because, in the case above the NIC capability is on board the server. However there is a recent trend of a disaggregated model (For example Open Compute Project OCP). In this form-factor, the CPU blades/chassis are separated from the NIC/Accelerator chassis, and Storage chassis. Inter-connection between the blades/chassis could be over optical fiber. So because of this reason NIC is mentioned separately as it owes its own explanation owing to its importance.
The main function of NIC is to provide network I/O functionality to/from CPU.
The vision of NFV is to run network functions on standard generic x86 servers. In practice however there are many I/O intensive applications ( for example virtual router) that would demand acceleration technologies to help improve I/O throughput of the machines.
Some hardware acceleration techniques involve the following:
· Hardware acceleration such as Digital Signal Processing (DSP), packet header processing, packet buffering and scheduling.
· Cache Management features.
Additions to the Instruction Set Architecture (ISA) (e.g. x86, ARMv8, etc.) which implement new software acceleration features.
3. Storage Building Block
The storage infrastructure includes different primary classifications of drives: Hard Disk Drives (HDDs), Solid State Disks (SDDs), Cache storage etc. which needs to be understood.
3.1 Hard Disk Drives
A hard disk drive (HDD), hard disk, is a data storage device that uses magnetic storage to store and retrieve digital information using one or more rigid rapidly rotating disks (platters) coated with magnetic material. The platters are paired with magnetic heads which read and write data on platter surface. Data is accessed in a random-access manner, which has the advantage that data can be retrieved in any order and not only sequentially. HDDs is non-volatile storage. Which means, it can retaining stored data even when powered off.
3.2 Solid State Disks (SSD)
Solid State Disks (SSDs), unlike HDDs, do not possess moving parts. Therefore, compared with HDDs, SSDs are typically more resistant to physical shock, run silently, and have lower access time and lower latency. So, they are a suitable technology for use in applications that demand considerable randomized accesses. They are comparatively expensive to HDD.
3.3 Hybrid Disk Drive
Increasing becoming popular, Hybrid hard drives offers HDD capacity with SSD speeds by placing traditional rotating platters and a small amount of high-speed flash memory on a single drive. So the beauty of Hybrid Disk drive is that they will utilize SSDs as a high-speed cache (or possibly as a tier) and will utilize HDDs for persistent storage.
So understanding the three parts: “Compute Node”, “NIC” and “Storage” completes the picture of Compute Domain and understanding these basic parts is really important as they form the server on which the complete NFV architecture is erected.
Drop a line to me if you found this basic understanding of the server useful to you?