XS Recommended Hardware

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This is a description of the hardware recommended for the School server. Unlike the current laptop, the school server is currently off-the-shelf (OTS) hardware. This document outlines general criteria for the School Server and has some specific notes about what we recommend for the XS.

Contents

Overview

Overall considerations

  • Known to be compatible with CentOS 6 which is a modern Linux distribution.
  • Low power consumption
  • Operation in environmentally challenging conditions

Hardware known to work

This hardware has been tested with the XS images - add your own, if possible with notes as to its suitability for the role

Used in development and testing:

  • HP/Compaq dx2250 - used by Martin Langhoff as test XS, low memory. Is RH-certified, and ships with a factory RH install.
  • Laptop Dell Latitude D380 - used by Martin Langhoff as test XS.
  • Dell PowerEdge SC440 - used by Martin Langhoff as test XS.

Hardware being used in the field -- compare Mitch Seaton's Apr 17, 2012 summary of 4 choices:

  • Asus Eee PC (1005PEB)
    • At Asilong Primary School in Asilong Kenya
    • Cost: $220
    • Additional hardware: 500 GB HDD $60, USB-Ethernet Adapter $10
    • Total number of users/laptops: 300/100
    • Usual max "concurrent" users: 30
    • Notes: Added AR81Family-Linux Driver to get Ethernet running, Modified /boot/grub/menu.lst to add "acpi_osi=Linux acpi_backlight=vendor" to end of Kernel command to get screen backlight to work. Contact andradupont@gmail.com for details
  • Acer Aspire One (532h)
    • At Asilong Primary School in Asilong Kenya
    • Cost: $275
    • Additional hardware: 500 GB HDD $60, USB-Ethernet Adapter $10
    • Total number of users/laptops: 300/100
    • Usual max "concurrent" users: 30
    • Notes: Added AR81Family-Linux Driver to get Ethernet running. Contact andradupont@gmail.com for details
  • MSI Wind
    • Who is using it? Where?
    • Cost: ??
    • Additional hardware used: ?
    • Total number of users/laptops: ?
    • Usual max "concurrent" users: ?
    • Notes: ?
  • FitPC - http://en.wikipedia.org/wiki/Fit-PC
    • Who is using it? Village deployment in Bhagmalpur: http://bhagmalpur.wordpress.com/ and http://wiki.laptop.org/go/OLPC_India/Bhagmalpur Where? Bhagmalpur, Uttar Pradesh, India. Google Map - http://tinyurl.com/bhagmalpur
    • Total number of users/laptops: 14 XO-1 laptops.
    • Usual max "concurrent" users: Can support bout 30.
    • Notes: x86 server running a AMD Geode processor. Pulls 8W on the AC end. The DC end uses a 12V input. Fanless. The body is aluminum based and acts as a heat sink. We are running the FitPC with a 64GB SSD. currently runs on XS 0.6 Uses a mesh antenna for LAN and Ethernet for WAN.
  • FitPC2 - http://fit-pc2.com/wiki/index.php?title=Main_Page
    • Who is using it? Where?
    • Cost: around USD$396
    • Additional hardware used: ?
    • Total number of users/laptops: ?
    • Usual max "concurrent" users: ?
    • Notes: ?
  • LogicPro (needs link -- is it a Logic Supply machine?)
    • Who is using it? Where?
    • Cost: around USD$435
    • Additional hardware used: ?
    • Total number of users/laptops: ?
    • Usual max "concurrent" users: ?
    • Notes: ?
  • Aleutia T1 - http://www.aleutia.com/products/t1
    • Used in Afghanistan
    • Cost around $320
    • Additional hardware used: N/A
    • Usual max "concurrent" users - 500
    • Notes: Fanless / Passively cooled, accepts 12V DC power supply (e.g. could connect to solar charge controller directly without) 2GB RAM Intel Atom Processor inc. 250 GB HDD power usage between 10-15W. BIOS also has 'switch on when power is restored' feature.

Hardware that could potentially be used

As our work is based on CentOS, the Hardware compatibility notes for Fedora and RHEL systems are the best guide. See:

In general, hardware that is certified to work with RHEL, CentOS or Fedora will work. Hardware certified or known to work with Debian or Ubuntu is extremely likely to work.

Qualifying HW for Linux

If the hardware is not certified and you need a strict process to ensure that it is appropriate for the task there are some useful test protocols here http://www.linux-tested.com/lnx_hardware.html - use the test protocols for:

  • Server / Workstation (focus on server, naturally)
  • LAN adapters - for every LAN adapter on the machine
  • SCSI adapters - if the server uses SCSI adapters

The same company offers independent testing services which may be appropriate in some cases.

Hardware Profile

  • 1GHz+ x86 processor
  • 2+ GB main memory
  • Four to six USB interfaces, with power for an external disk drive. Ensuring the ports can power various devices at the same time is recommended.
  • One 1TB 3.5in SATA drive (smaller drives are now hard to find)
  • Power and space for a second disk drive
  • Two ethernet network interfaces (one will do in some cases)
  • Minimal fans
    • Replace them with heatsinks where possible
    • Easily replaceable
  • Minimal openings in the case to avoid dust, etc
  • Test it in the heat - should work in up to 50 deg C

Scaling up

For larger schools, add RAM, disk storage and CPU (in that order). The current XS design does not need, and does not support, splitting services across many machines. See XS Load Testing for details on load testing of different XS configurations.

Server Sizing

At the moment, we are recommending

  • Schools with less than 40 laptops can use XS-on-XO, which requires an SD card, an external USB harddrive (at least 2GB per laptop), and a USB-Ethernet.
  • Schools with up to 100 laptops: a 1GHz CPU, 1GB RAM
  • For up to 500 laptops: dual-core 2GHz CPU, 2~4GB RAM
  • More than 500 laptops: Server-class dual CPU, 4~16GB RAM

HDD Storage needs to be sized according to the laptop's storage capacity:

  • XO-1: 800MB storage per laptop
  • Units later than XO-1 have variable storage
    • 2GB storage: 2GB per laptop
    • 4GB storage: 3GB per laptop
    • 8GB storage: 7GB per laptop

It is OK to underprovision storage by a modest margin. The server stores backups in an efficient mode where duplicate files are identified and consolidated.


Note! For any school larger than 30 laptops, you also need careful planning of the wireless network setup.

Environmental notes

The location where the HW will be deployed determines the environmental requirements. Our guidelines are as follows:

  • Temperature: Should meet the same environmental specifications for temperature as the laptop. This is 50 C ambient.
  • Dust: For dusty environments, the hardware should be in an enclosure without vents, have no fans, and have protection for ports such as USB ports.
  • Water, humidity: For humid environments the server should be capable of long-term operation in a constantly humid (100%) environment.
  • 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.

Other considerations

  • Mounting: the hardware should be able to run from a flat surface or be mounted on a wall and/or hangable.
  • Drop and Shake: should meet higher drop and shake specifications than standard consumer desktop PCs, to account for rough transport in the delivery.
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