Computer cluster

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Computer cluster – Wikipedia, the free encyclopedia.

A computer cluster is a group of linked computers, working together closely thus in many respects forming a single computer. The components of a cluster are commonly, but not always, connected to each other through fast local area networks. Clusters are usually deployed to improve performance and availability over that of a single computer, while typically being much more cost-effective than single computers of comparable speed or availability.[1]

And now I will put together clusters for high availability and load balancing.  This is where VMs come in handy.   I think I  prefer loosely coupled clusters, clusters where individual nodes are separated on different power grids.

It’s always nice to have a succinct definition handy to stay focused.

Xen Guest (DomU) Installation

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xm commands

List Domains (Xen Guests)

# xm list

Start a Guest

# xm create [guest-config]

Connect to a guest console ( Back: ESC-] (US-keyboard), Ctrl-5 (German keyboard))

# xm console [guest_name]

Shutdown a guest

# xm shutdown [guest_name]

Destroy (Power off) a guest

# xm destroy [guest_name]

Monitor guests

# xm top

virsh commands

# virsh

virsh # help

 

virsh start [guest_name]

via Xen Guest (DomU) Installation « Thomas Vogt’s IT Blog.

OpenWrt

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OpenWrt is described as a Linux distribution for embedded devices.

Instead of trying to create a single, static firmware, OpenWrt provides a fully writable filesystem with package management. This frees you from the application selection and configuration provided by the vendor and allows you to customize the device through the use of packages to suit any application. For developer, OpenWrt is the framework to build an application without having to build a complete firmware around it; for users this means the ability for full customization, to use the device in ways never envisioned.

via OpenWrt.

Steve Jobs Solved the Innovator’s Dilemma

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By taking this approach, Apple bent all the rules of disruption. To disrupt yourself, for example, Professor Christensen’s research would typically prescribe setting up a separate company that eventually goes on to defeat the parent. It’s incredibly hard to do this successfully; Dayton Dry Goods pulled it off with Target. IBM managed to do it with the transition from mainframes to PCs, by firewalling the businesses in entirely different geographies. Either way, the number of companies that have successfully managed to do it is a very, very short list. And yet Apple’s doing it to itself right now with the utmost of ease. Here’s new CEO Tim Cook, on the iPad disrupting the Mac business: “Yes, I think there is some cannibalization… the iPad team works on making their product the best. Same with the Mac team.” It’s almost unheard of to be able to manage disruption like this.

via Steve Jobs Solved the Innovator’s Dilemma – James Allworth – Harvard Business Review.

Enterprise Storage Encryption: An Administrator’s …

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Storage encryption has historically proven unpopular because of the issues of managing the keys used in various encryption methods, and the system performance burden that encryption/decryption placed on systems hardware. These issues have been iteratively surmounted in a number of advances. Faster CPUs, disk controllers and host bus adapters (HBAs) and tough-to-break encryption now reduce the burden once placed on subsystem, disk, and device encryption.

via Enterprise Storage Encryption: An Administrator’s … – Input Output.

This is a pretty good article.  Here’s one more blurb.

Subsystems are encrypted at the hardware level or at the device group level. Subsystems can also be encrypted by the use of third-party software packages designed specifically for this purpose. Subsystem encryption usually means that a single encryption key is used for the group, and that the private encryption key is stored in hardware or in system firmware. This type of protection means that a drive “stolen” or otherwise removed from the group of storage media can’t be decrypted, even by examining the disk using an identical system, as the identical system would be missing the key that unlocks the data by decrypting it.

This seems like a rather high level of security.