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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The initial spec is an OLPC laptop with attached USB hard drive and USB CD reader. It is still low-power enough that it could be powered by car batteries which are charged using a bicycle-generator made from an old car alternator. To conserve battery power, the USB hard-drive can be removed when it is not in use. |
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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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As this is a very limited production model, flexibility wins out over cost |
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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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*Consumer PC hardware ? |
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*x86 family for immediate development of software |
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*UPS used in trial deployments ? |
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==Processor== |
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==XS Specifications== |
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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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This is the hardware for deployment. |
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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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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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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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It may or may not be based on an x86 platform. |
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The pros and cons are: ... (feel free to editorialize) |
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==Network Interfaces== |
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=Software Specifications= |
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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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The [[School server]] should run roughly the same Linux OS as that in the XO laptop. |
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The following peripheral interfaces are provided for expanding the capabilities of the school server. |
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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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===USB 2.0=== |
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==Development Toolchain== |
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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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What is the cost of this toolchain being different from that used for the XO laptop? |
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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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==Upgrades== |
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===PCI-Express Slot=== |
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How is the [[School server]] upgraded ? |
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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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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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==Service Management== |
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==Non-Volatile Storage== |
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How are services on the School server installed, configured, managed, and updated ? |
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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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A web based interface is a natural candidate for performing these actions on the [[School server]]. |
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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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A fan-less aluminum disk drive cooler may be worthwhile as a prevention of overheating measure. |
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==Scalability== |
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===External Disk Drives=== |
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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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Additional disks may be added using the external USB 2.0 ports. |
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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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A smaller amount (512KB) of NOR Flash will be provided for storage of configuration information and boot firmware. |
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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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==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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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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Possible methods of obtaining power are summarized in [[Battery_and_power]]. |
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==Environmental== |
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===Temperature=== |
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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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While the server will contain fans, they will externally accessible for easy replacement and under software control to conserve power. |
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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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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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===Drop and Shake=== |
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The [[school server]] should meet higher drop and shake specifications than standard consumer |
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desktop PCs, to account for rough transport in the delivery. |
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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.