Help Activity refresh/Chapter/XS school server: Difference between revisions
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(Created page with '==Hardware== The selection of the school server hardware should take into account a number of factors: *How many XO's will be connected? **A low power 30 watt Atom processor, s…') |
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==Hardware== |
==Hardware== |
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The selection of the school server hardware should take into account a number of factors: |
The selection of the school server hardware should take into account a number of factors: |
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*How many XO's will be connected? |
*How many XO's will be connected to the school server at a given time, and over the period of the school term (say, a semester or year)? |
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**A low power 30 watt Atom processor, such as the Solid Logic http://www.logicsupply.com/products/atom_jt01s can support up to 60-100 students. 1 Gb of RAM and about 2 GByte of disk space for every XO |
**A low power 30 watt Atom processor-based server, such as the Solid Logic http://www.logicsupply.com/products/atom_jt01s can support up to 60-100 students. This server has 1 Gb of RAM and about 2 GByte of disk space for every XO |
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**An 80 watt core i3 64bit processor might support 150-300. |
**An 80 watt core i3 64bit processor might support 150-300. |
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**A top of the line core i7 quad or itanium processor might need 4 Gbyte, 1.5TB, and can handle 300-500 XO's. |
**A top of the line core i7 quad or itanium processor might need 4 Gbyte, 1.5TB, and can handle 300-500 XO's. |
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*#How much power is available during a 24 hour period? Will the server be connected to the grid? Is the grid reliably on during school hours? If not, how big does the battery need to be to supply power during school hours? If power is not dependable enough during a 24 hour period, maybe solar power will be required. |
*#How much power is available during a 24 hour period? Will the server be connected to the grid? Is the grid reliably on during school hours? If not, how big does the battery need to be to supply power during school hours? If power is not dependable enough during a 24 hour period, maybe solar power will be required. |
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*#The power consumption of the server times the number of hours in the school day will determine the number of watt-hours that must be stored in a deep-cycle storage battery. Batteries are usually rated in Ampere-hours. A 12 volt battery with a 100 Amp-hour capacity, holds 1200 watt-hours. Batteries last longer if they are cycled through only about 50% of their total capacity. So you can use about 600 watt-hours from a 100AHr battery. This can keep a 120 watt server alive for 5 hours, or a 30 watt server for 20 hours. |
*#The power consumption of the server times the number of hours in the school day will determine the number of watt-hours that must be stored in a deep-cycle storage battery. Batteries are usually rated in Ampere-hours. A 12 volt battery with a 100 Amp-hour capacity, holds 1200 watt-hours. Batteries last longer if they are cycled through only about 50% of their total capacity. So you can use about 600 watt-hours from a 100AHr battery. This can keep a 120 watt server alive for 5 hours, or a 30 watt server for 20 hours. |
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*#An intelligent |
*#An intelligent Uninteruptible Power Supply (UPS), capable of communication with the server (typically via serial or USB cable), should be installed so that the server can properly shut itself down, when battery power is almost exhausted. In addition to the school server itself, networking hardware must be purchased. For purposes of planning, there should be one access point (AP) for each 50 XO's. With multiple AP's, there will need to be a 5-8 port ethernet switch installed close to the school server. |
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In addition to the school server itself, networking hardware must be purchased. For purposes of planning, there should be one access point (AP) for each 50 XO's. With multiple AP's, there will need to be a 5-8 port ethernet switch installed close to the school server. |
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Access points can be configured to use 11 channels, but really only 3 channels are non-interfering (channels 1,6,and 11). |
Access points can be configured to use 11 channels, but really only 3 channels are non-interfering (channels 1,6,and 11). |
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Revision as of 19:55, 7 April 2012
Hardware
The selection of the school server hardware should take into account a number of factors:
- How many XO's will be connected to the school server at a given time, and over the period of the school term (say, a semester or year)?
- A low power 30 watt Atom processor-based server, such as the Solid Logic http://www.logicsupply.com/products/atom_jt01s can support up to 60-100 students. This server has 1 Gb of RAM and about 2 GByte of disk space for every XO
- An 80 watt core i3 64bit processor might support 150-300.
- A top of the line core i7 quad or itanium processor might need 4 Gbyte, 1.5TB, and can handle 300-500 XO's.
- Adequate power for a school server is often difficult to achieve.
- How much power is available during a 24 hour period? Will the server be connected to the grid? Is the grid reliably on during school hours? If not, how big does the battery need to be to supply power during school hours? If power is not dependable enough during a 24 hour period, maybe solar power will be required.
- The power consumption of the server times the number of hours in the school day will determine the number of watt-hours that must be stored in a deep-cycle storage battery. Batteries are usually rated in Ampere-hours. A 12 volt battery with a 100 Amp-hour capacity, holds 1200 watt-hours. Batteries last longer if they are cycled through only about 50% of their total capacity. So you can use about 600 watt-hours from a 100AHr battery. This can keep a 120 watt server alive for 5 hours, or a 30 watt server for 20 hours.
- An intelligent Uninteruptible Power Supply (UPS), capable of communication with the server (typically via serial or USB cable), should be installed so that the server can properly shut itself down, when battery power is almost exhausted. In addition to the school server itself, networking hardware must be purchased. For purposes of planning, there should be one access point (AP) for each 50 XO's. With multiple AP's, there will need to be a 5-8 port ethernet switch installed close to the school server.
Access points can be configured to use 11 channels, but really only 3 channels are non-interfering (channels 1,6,and 11).