Posts from Alex Bligh

Containers vs Hypervisors and Other Considerations

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Cloud Service Providers
A hypervisor is one of two main ways to segment a physical machine into multiple virtual machines; the other significant method is to use containers. A hypervisor segments the hardware by allowing multiple guest operating systems to run on top of it. In a container system, the host operating is itself divided into multiple containers, each running a virtual machine. Each virtual machine thus not only shares a single type of operating system, but also a single instance of an operating system (or at least a single instance of a kernel).

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Service Providers, Cloud Security and FUD

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Security- Software as a (Single Tenant) Service?One of the biggest barriers to adopting a cloud-based approach to IT services has been security – or a perceived lack of security. The good news though is that some analysts believe we are getting past this. For cloud service providers though, it means adding value on top of their cloud services by being an expert in this space.

The case for cloud has been hindered by a number of high profile reports of hacking leading to what industry analysts have termed ‘FUD’: fear, uncertainty and doubt.

These perceptions have affected the business community too, with many organizations believing the cloud to be less secure than an on-premise alternative.
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What is Cloud Scalability & How to Deal with Failure

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Cloud Network Scalability

What is Scalability?

Scalability concerns the ability of a cloud system to scale, and the cost and performance implications of doing so. As any cloud system is made up of a multitude of components, cloud scalability raises two questions:

1. Is there a maximum size of any part of the system?
2. If the size of a system is doubled, for example, does that mean the cost of running it (technical or otherwise) doubles, less than doubles, or more than doubles?

Scalability issues thus result in a maximum size and an optimum size (where the cost of providing service is lowest).
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What is Cloud Scalability & How to Deal with Failure

Posted on

Cloud Network Scalability

What is Scalability?

Scalability concerns the ability of a cloud system to scale, and the cost and performance implications of doing so. As any cloud system is made up of a multitude of components, cloud scalability raises two questions:

1. Is there a maximum size of any part of the system?
2. If the size of a system is doubled, for example, does that mean the cost of running it (technical or otherwise) doubles, less than doubles, or more than doubles?

Scalability issues thus result in a maximum size and an optimum size (where the cost of providing service is lowest).
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Network Scalability: Layer 2 Issues

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Cloud Network Scalability

To overcome cloud networking scalability challenges as outlined in a previous blog post, cloud service providers look to solutions like Layer 2, VLANs and Layer 3. Discussed below are the issues service providers face with Layer 2.

Layer 2 issues

One of the first challenges in scaling the cloud provider’s network comes at layer 2.

To explain this, it is first necessary to recap how a switched Ethernet network works. Each network interface card (physical or virtual) participating in a layer 2 network has a unique MAC address. Each packet contains a header (the MAC header) containing the source and destination MAC address of the sending and receiving network interface. The switches on the layer 2 network learn the source addresses of any packet passing through them. When a switch comes to forward a packet to a given destination, it looks up that destination in the forwarding table that it has learnt, and if an entry is present, the packet is forwarded to that port. If an entry is not present (or if the packet is a broadcast packet), the packet is forwarded to all ports. Such forwarding to all ports is to be avoided as they use bandwidth on each port as well as switch capacity. It is thus vital the forwarding table can contain entries for all source MAC addresses in use.
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