XS Server Hardware

This is a description of the first implementation of the School server. It describes the hardware and software implementation details, including the management of services. The actual services provided by the School server are described in the Server Services document, with an accompanying discussion of desired services.

Hardware Specifications

The School server hardware platform has not been selected at this time.

The current plan is to provide two hardware platforms. One, XSX, available by mid-March, will allow for School server software testing and early deployments in areas where power mains are at least periodic if not continuous. The second platform, XS, would be reduced in cost and power, and should be available for deployment beginning in October.

XSX Specifications

This is a version with a target date of mid-March. The primary goal is to support development of the School server/laptop software, including early trials.

The initial spec is similar to an OLPC laptop with attached USB hard drive and USB CD reader. The only defined aspect is an x86 family processor.

As this is a very limited production model (10s - 100 ?), flexibility wins out over cost. Consumer PC hardware is a possibility.

There are no power consumption targets for this device. A UPS may be suggested for trial deployments in areas of uncertain power.

XS Specifications

This is the hardware platform for actual deployment.

The school server must meet all of the environmental constraints of the XO laptop with the exception of daily rough handling!

Processor Architecture

This hardware platform may or may not be based on an x86 platform. "Add your own reasons here."

Reasons to use x86

• Support required for only a single toolchain
• Able to use an XO as an emergency school server replacement ?

Reasons to use non-x86

• Lower power
• Lower cost
• Usually integrated with more onchip peripherals.

Network Interfaces

What network interfaces should be provided on the School server ?

802.11b/g

How many WiFi interfaces should be built into the server ?

If we really have 100 students in close proximity, can we make do with only one channel ?

The number of WiFi interfaces can be expanded using external, USB connected WiFi nodes. A reasonable number of these (four to six) can be added to a server to increase the WiFi performance.

100baseT

A wired ethernet interface provides for reliable, high-bandwidth connection between school servers, or a school server and a DSL/satellite modem.

The current plan is to include at least one, probably two 100baseT ports on the server.

Powerline

This technology has the potential to provide 100baseT performance over the power lines used to power the school server.

The advantage is that even if power lines aren't currently deployed in the school, the cable required for powerline networking is more likely to be available/cheaper than Cat-3 or Cat-5 cable.

A drawback is the lack of standardisation and regulatory concerns in many nations. Correcting the regulatory situation isn't necessarily just a matter of time. Powerline networking emits strongly in the lower HF band, increasing the noise floor for existing communication systems (not WiFi, WiMax or cellular).

Other Interfaces

What other interfaces should the School server have ?

USB 2.0

A number of USB 2.0 interfaces should be provided.

Perhaps four ports, on two separate buses ?

Internal Disk

Should an internal disk drive be provided ? A bare SATA disk is cheaper than a USB disk, and almost as easy to connect/disconnect.

Power

The possible methods of obtaining power are summarized in Battery_and_power.

Software Specifications

The School server should run roughly the same Linux OS as that in the XO laptop. The release process will probably be different, but the kernel and most libraries should be identical.

Development Toolchain

What is the cost of this toolchain being different from that used for the XO laptop?

Upgrades

How is the School server upgraded ?

Service Management

How are services on the School server installed, configured, managed, and updated ?

A web based interface is a natural candidate for performing these actions on the School server.

Scalability

A School server should serve up to sixty students. In schools with more students, how are the servers interconnected to minimize the management overhead ?

Ideally, the number of students supported by a single server results in at least two servers in a typical school, providing a degree of redundancy.

The management interface for a school should be independent of the number of servers needed to serve the school.