Blade Optimized Virtual Server Load Balancing Solution

For blade servers I have experienced several different stages from love to rejection to today's love.

Before entering the virtual architecture, blade servers have had several stages of development until they are used in today's virtual environments and can yield many additional benefits. By integrating multiple servers in a single blade enclosure, you can improve the load balancing scheme for virtual servers and address a range of issues surrounding server updates.

Blade Challenges in the Pre-Virtualization Age

Blade servers emerged earlier than virtualization, and one of their main selling points at the time was their automated management capabilities. I still remember the early hardware vendors' step-by-step demonstration of how to pull a blade out of the cabinet and replace it with a new one. At that time, the management tool can identify the replaced component and automatically rebuild the operating system of the original blade on the replaced hardware.

The purpose of this is to achieve a quick replacement of the faulty part. If a blade fails, simply unplug it from the cabinet and insert a new one. The rest is left to the management tool to complete.

However, it is difficult for most users to implement this completely automated application, in part because it is too difficult. The automatic rebuild process is still very complicated before virtualization occurs. It takes a lot of time to create an available operating system image, and these images are constantly changing, further increasing the difficulty of implementing on a physical server.

Early Blade Servers: Vendor Commitment

Later, virtualization began to evolve, indirectly driving the second wave of blade server development. According to the manufacturer's suggestion, due to the characteristics of the blade, it can be combined with virtualization: after failure, it can be replaced with a new blade server, and then wait for the automatic reconstruction of the virtual host operating system.

But the biggest difference this time is that the OS of the virtual host is completely stateless. Since most of the changes happen on the child virtual machine, it is easy for the host OS to make the "hot plug" option mode.

In this second phase, I still reject the use of blades. After all, what the manufacturer claims, the early generation of blade cabinets is not designed for virtualization. It is limited to only 2 or 4 Gigabit NIC interfaces, which is not enough for most virtual architectures. Some blades also have limitations on the number of fiber-optic host adapters, which has led to a significant bottleneck in hardware configuration in applications where performance requirements are at the top.

Blade Servers for Virtualization

Today, these early port limitations no longer exist, and hardware vendors have finally entered the field. Even some blades and cabinets are designed for virtualization, supporting multiple 1Gb and 10Gb NICs and a large number of FC interfaces.

The manageability and automation of the blades has also been greatly enhanced. Combined with VMware's near-stateless ESXi hypervisor and Microsoft's lightweight Windows Server Core, it is easy to rebuild a new host OS after the blade is replaced.

More importantly, automation at the blade level and automation at the virtual machine hypervisor level are organically combined. Blade failures (or sometimes warnings) can be quickly reflected in VMware vSphere or Microsoft's SCVMM (System Center Virtual Machine Manager), and virtual machines can be migrated.

Once the virtual machine is migrated to another host, it is easy to rebuild the OS on the new host that was replaced by the original location. The host can be enabled very quickly. In the end, it was a reality to automate the manual replacement of blade servers ten years ago.

Blade Servers and Replacement Issues

Blade servers have significant advantages in terms of virtual machine migration and management.

This generation of blade servers solves one of the most painful and difficult to understand long-term problems in private cloud computing systems: the limitations imposed by technology updates. After several generations of system architecture development, it will be very difficult to implement online migration between new servers and old servers, including load balancing between different virtual machines.

In my recent book, "Private Cloud: Choosing the Right Hardware to Build an Elastic Virtual Machine Architecture," I discussed the issues that may arise from hardware replacement in virtual and private cloud systems: "Virtual Environment... Because of its resource abstraction ability, it can extend the service life of traditional servers. The problem is that sometimes the compatibility between different generations of hardware is not very good."

Different generation hardware problems on virtual machine load The impact of equalization and online migration capabilities is particularly obvious, and they all require the same configuration of the source and target hosts. For example, it is well known that online migration between AMD and Intel platforms is not possible.

And, you may not notice that even the same manufacturer's processor needs to be basically similar. The CPU relationship that supports vMotion is listed in the "VMware knowledgebase article" article, which seems to be narrower than expected.

In the short term, with the extension of the virtual infrastructure life cycle, the issue of replacement will be very common. Whenever a new server is added, the problem that a newly purchased server cannot be combined with the previous online migration is likely to exist.

Blade Enclosure Optimizes Server Load Balancing

And that's where blade servers take advantage. A blade cabinet can solve the problem caused by the replacement. Blades in the same cabinet are much more compatible with this problem than regular servers. This means that you can freely load balance the virtual servers in the same cabinet, although it may not be supported across the cabinet, but this is sufficient for most enterprise needs.

As time goes by and hardware builds up, the gap between generations becomes more and more prominent, so it's time to consider the virtualization-specific blade cabinets recommended by hardware vendors and other similar products.