XS Server Hardware: Difference between revisions
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This is a description of the first implementation of the [[School server]]. |
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{{OLPC}} |
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It describes the hardware and software implementation details, including the |
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[[Category:SchoolServer]] |
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management of services. The actual services provided by the [[School server]] |
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are described in the [[XS_Server_Services|Server Services]] document, with an |
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accompanying [[XS_Server_Discussion|discussion of desired services]]. |
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'''Note: If you are looking for a Hardware Recommendation for School Server, see [[XS_Recommended_Hardware]]. This page discusses a custom hardware platform created by OLPC for the School Server role.''' |
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=Hardware Specifications= |
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=Introduction= |
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The School server hardware platform has not been selected at this time. |
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(As of mid-2008, the plans discussed here are on hold.) |
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The current plan is to provide two hardware platforms. One, XSX, available by mid-March, |
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will allow for School server software testing and early deployments in areas where |
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power mains are at least periodic if not continuous. The second platform, XS, would be |
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reduced in cost and power, and should be available for deployment beginning in |
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October. |
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In the medium-term we expect to provide a number of [[School server]] hardware platforms. OLPC, in order to support the deployment of laptops, especially in environmentally hostile or off-the-grid locations, is designing a reference platform in collaboration with our manufacturing partner, Quanta. |
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==XSX Specifications== |
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Planned platforms include: |
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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. |
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* [[XSX Server Implementation|XSX]] - A medium-term prototype, using OTS parts |
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* An XO laptop - Equipped with an external disk drive, a laptop should be capable of performing as a school server for small (less than thirty laptop) schools. |
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* XS - An environmentally rugged, very low power school server for up to 150 students. Should be available in November. |
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=XS Specifications= |
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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. |
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This is a [[School server]] hardware platform designed with low power consumption and operation in environmentally challenging conditions as goals. |
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As this is a very limited production model (10s - 100 ?), flexibility wins out over cost. |
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Consumer PC hardware is a possibility. |
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==Processor== |
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There are no power consumption targets for this device. A UPS may be suggested for trial deployments |
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in areas of uncertain power. |
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This hardware platform may be based on any processor architecture supported by the mainstream Linux kernel and libc software trees. We encourage the use of processors supported by Fedora Core 7. |
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==XS Specifications== |
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Processor performance is difficult to characterize with a single number. We are looking for between 1200 and 1600 MIPs, capable of 120K+ interrupts/sec, with at least 1 GB/sec of memory throughput. At least 256KB of L2 cache should be provided. |
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This is the hardware platform for actual deployment. |
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For the XS Server, the processor is a PowerPC, the MPC7447A from Freescale, with AltiVec support. Apple calls it a G4. |
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The school server must meet all of the environmental constraints of the XO laptop |
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with the exception of daily rough handling! |
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==Network Interfaces== |
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===Processor Architecture=== |
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The following are the integrated networking interfaces on XS. Additional interfaces may be added to the system using the [[#Peripheral_Interfaces|peripheral interfaces]]. |
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==Peripheral Interfaces== |
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This hardware platform may or may not be based on an x86 platform. "Add your own reasons here." |
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The following peripheral interfaces are provided for expanding the capabilities of the school server. |
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=== |
===USB 2.0=== |
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At least six [http://en.wikipedia.org/wiki/USB Universal Serial Bus] (USB) 2.0 interfaces should be provided for extending the storage and communication capabilities of a [[School server]]. |
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This assumes that up to three external ports will be used for [[Active Antenna]], another for an external CD/DVD RW, another for a possible WAN connection, and one last one for temporary USB key or external USB drive attachment. |
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*Support required for only a single toolchain |
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*Able to use an XO as an emergency school server replacement ? |
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The total amount of power consumed by the USB devices will be clamped to 2.5 A at 5 Volts (12.5 W) total, aggregrated across all devices. Any single device may pull up to 1.5 A (7.5 W). |
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====Reasons to use non-x86==== |
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===PCI-Express Slot=== |
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*Lower power |
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A short, full height PCI-Express (4 channel) expansion slot is provided internally in the XS. This slot is intended for the addition of a DVB-S receiver and demodulator, but may be used for other purposes as well. |
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*Lower cost |
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*Usually integrated with more onchip peripherals. |
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The power consumption of this expansion slot limited to 15 W. Exceeding this will lower the maximum ambient operating temperature of the server, and may also prevent the use of a second disk drive. |
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===Network Interfaces=== |
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==Non-Volatile Storage== |
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What network interfaces should be provided on the School server ? |
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''to consider : how many drives are recommended for backups and replacement? with only 1 drive, what is the path to recovering a dead/dying drive? this may depend on quality of connection between server and upstream backup at a regional center'' |
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=== |
===Internal Disk Drive=== |
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One internal 3.5 in. disk drive will be provided. The disk interface will be SATA (version 1 or 2). The capacity of this disk drive WILL vary, with a minimum size of 300 GB at this time. |
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A second 3.5 in. disk drive will be supported in the XS, primarily for onsite drive replacement, but also allowing storage expansion. Use of a second disk drive will significantly increase the power consumption of the server. |
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How many interfaces should be provided ? If we really have 60 students in close |
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proximity, can we make do with only one or two channels ? |
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A fan-less aluminum disk drive cooler may be worthwhile as a prevention of overheating measure. |
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====100baseT==== |
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===External Disk Drives=== |
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A wired ethernet interface provides for reliable, high-bandwidth connection between |
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school servers, or a school server and a DSL/satellite modem. |
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Additional disks may be added using the external USB 2.0 ports. |
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Perhaps the question is "How many Cat5 ports should the School server provide ?" |
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=== |
===Flash=== |
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A fair amount (512 MB) of NAND Flash (solid state non-volatile) memory will be provided on the XS server to allow the operating system and minimal services to continue operation even though the primary disk drive has failed. |
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This technology has the potential to provide 100baseT performance over the power lines used |
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to power the school server. |
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A smaller amount (512KB) of NOR Flash will be provided for storage of configuration information and boot firmware. |
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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. |
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On OTS systems Flash storage is currently not needed - or used. If you can obtain flash disks for all your OTS XS machines, do discuss it in the mailing list - it is an extremely valuable addition.we are considering using adding USB keys or SD cards to allow similar functionality. |
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The 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). |
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==Power== |
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The power specifications of the [[School server]] are important. Many schools do not have adequate, or regular, power. While the power consumption should be minimized (30W is a good |
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===Other Interfaces=== |
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target), consideration should be given to an integral (or optional modular) uninterruptible power supply (UPS). This is nothing more than a larger version of the laptop power supply! |
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In some test schools with minimal power, we are already deploying multiple (gang) battery chargers with integral UPS. |
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What other interfaces should the School server have ? |
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Possible methods of obtaining power are summarized in [[Battery_and_power]]. |
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====USB 2.0==== |
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==Environmental== |
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A number of USB 2.0 interfaces should be provided. |
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===Temperature=== |
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Perhaps four ports, on two separate buses ? |
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The [[school server]] should meet the same environmental specifications for temperature as the laptop. This is 50 C ambient. |
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===Water, Dust, and Salt Fog=== |
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The server should be resistant to water spray from all directions, but does not have to survive immersion. It should be capable of long-term operation in a constantly humid (100%) environment, with salt fog and dust. |
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===Internal Disk=== |
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While the server will contain fans, they will externally accessible for easy replacement and under software control to conserve power. |
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Should an internal disk drive be provided ? A bare SATA disk is cheaper than a USB disk, and almost as easy to connect/disconnect. |
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Connectors and buttons should be resistant to water and dust intrusion. Buttons should be sealed against water, and connectors located and cables dressed to prevent water intrusion. |
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=== |
===Mounting=== |
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While the school server should be designed to sit on a flat surface, it should probably |
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The possible methods of obtaining power are summarized in [[Battery_and_power]]. |
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also be mountable (hangable) from a wall or post. |
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This shouldn't cause a problem unless the server includes batteries for a optional/modular UPS... |
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=Software Specifications= |
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===Drop and Shake=== |
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The [[School server]] should run roughly the same Linux OS as that in the XO laptop. |
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The release process will probably be different, but the kernel and most libraries should be |
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identical. |
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The [[school server]] should meet higher drop and shake specifications than standard consumer |
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==Development Toolchain== |
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desktop PCs, to account for rough transport in the delivery. |
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What is the cost of this toolchain being different from that used for the XO laptop? |
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==Upgrades== |
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How is the [[School server]] upgraded ? |
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==Service Management== |
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How are services on the School server installed, configured, managed, and updated ? |
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A web based interface is a natural candidate for performing these actions on the [[School server]]. |
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==Scalability== |
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A [[School server]] should serve up to sixty students. In schools with more students, how |
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are the servers interconnected to minimize the management overhead ? |
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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. |
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The management interface for a school should be independent of the number of servers needed to serve the school. |
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Latest revision as of 15:41, 12 December 2009
| Please copy/paste "{{Translationlist | xx | origlang=en | translated={{{translated}}}}}" (where xx is ISO 639 language code for your translation) to XS Server Hardware/translations | HowTo [ID# 227425] +/- |
Note: If you are looking for a Hardware Recommendation for School Server, see XS_Recommended_Hardware. This page discusses a custom hardware platform created by OLPC for the School Server role.
Introduction
(As of mid-2008, the plans discussed here are on hold.)
In the medium-term we expect to provide a number of School server hardware platforms. OLPC, in order to support the deployment of laptops, especially in environmentally hostile or off-the-grid locations, is designing a reference platform in collaboration with our manufacturing partner, Quanta.
Planned platforms include:
- XSX - A medium-term prototype, using OTS parts
- An XO laptop - Equipped with an external disk drive, a laptop should be capable of performing as a school server for small (less than thirty laptop) schools.
- XS - An environmentally rugged, very low power school server for up to 150 students. Should be available in November.
XS Specifications
This is a School server hardware platform designed with low power consumption and operation in environmentally challenging conditions as goals.
Processor
This hardware platform may be based on any processor architecture supported by the mainstream Linux kernel and libc software trees. We encourage the use of processors supported by Fedora Core 7.
Processor performance is difficult to characterize with a single number. We are looking for between 1200 and 1600 MIPs, capable of 120K+ interrupts/sec, with at least 1 GB/sec of memory throughput. At least 256KB of L2 cache should be provided.
For the XS Server, the processor is a PowerPC, the MPC7447A from Freescale, with AltiVec support. Apple calls it a G4.
Network Interfaces
The following are the integrated networking interfaces on XS. Additional interfaces may be added to the system using the peripheral interfaces.
Peripheral Interfaces
The following peripheral interfaces are provided for expanding the capabilities of the school server.
USB 2.0
At least six Universal Serial Bus (USB) 2.0 interfaces should be provided for extending the storage and communication capabilities of a School server.
This assumes that up to three external ports will be used for Active Antenna, another for an external CD/DVD RW, another for a possible WAN connection, and one last one for temporary USB key or external USB drive attachment.
The total amount of power consumed by the USB devices will be clamped to 2.5 A at 5 Volts (12.5 W) total, aggregrated across all devices. Any single device may pull up to 1.5 A (7.5 W).
PCI-Express Slot
A short, full height PCI-Express (4 channel) expansion slot is provided internally in the XS. This slot is intended for the addition of a DVB-S receiver and demodulator, but may be used for other purposes as well.
The power consumption of this expansion slot limited to 15 W. Exceeding this will lower the maximum ambient operating temperature of the server, and may also prevent the use of a second disk drive.
Non-Volatile Storage
to consider : how many drives are recommended for backups and replacement? with only 1 drive, what is the path to recovering a dead/dying drive? this may depend on quality of connection between server and upstream backup at a regional center
Internal Disk Drive
One internal 3.5 in. disk drive will be provided. The disk interface will be SATA (version 1 or 2). The capacity of this disk drive WILL vary, with a minimum size of 300 GB at this time.
A second 3.5 in. disk drive will be supported in the XS, primarily for onsite drive replacement, but also allowing storage expansion. Use of a second disk drive will significantly increase the power consumption of the server.
A fan-less aluminum disk drive cooler may be worthwhile as a prevention of overheating measure.
External Disk Drives
Additional disks may be added using the external USB 2.0 ports.
Flash
A fair amount (512 MB) of NAND Flash (solid state non-volatile) memory will be provided on the XS server to allow the operating system and minimal services to continue operation even though the primary disk drive has failed.
A smaller amount (512KB) of NOR Flash will be provided for storage of configuration information and boot firmware.
On OTS systems Flash storage is currently not needed - or used. If you can obtain flash disks for all your OTS XS machines, do discuss it in the mailing list - it is an extremely valuable addition.we are considering using adding USB keys or SD cards to allow similar functionality.
Power
The power specifications of the School server are important. Many schools do not have adequate, or regular, power. While the power consumption should be minimized (30W is a good target), consideration should be given to an integral (or optional modular) uninterruptible power supply (UPS). This is nothing more than a larger version of the laptop power supply!
In some test schools with minimal power, we are already deploying multiple (gang) battery chargers with integral UPS.
Possible methods of obtaining power are summarized in Battery_and_power.
Environmental
Temperature
The school server should meet the same environmental specifications for temperature as the laptop. This is 50 C ambient.
Water, Dust, and Salt Fog
The server should be resistant to water spray from all directions, but does not have to survive immersion. It should be capable of long-term operation in a constantly humid (100%) environment, with salt fog and dust.
While the server will contain fans, they will externally accessible for easy replacement and under software control to conserve power.
Connectors and buttons should be resistant to water and dust intrusion. Buttons should be sealed against water, and connectors located and cables dressed to prevent water intrusion.
Mounting
While the school server should be designed to sit on a flat surface, it should probably also be mountable (hangable) from a wall or post.
This shouldn't cause a problem unless the server includes batteries for a optional/modular UPS...
Drop and Shake
The school server should meet higher drop and shake specifications than standard consumer desktop PCs, to account for rough transport in the delivery.