Raspberry Pi Cloud:a thought experiment

Richard DownerTwitter: @FrontierTown

GitHub: richardcloudsoft & rdownerPrincipal Engineer @ Cloudsoft Corporation

This presentation is my own work and may not represent the views of my employer

What is a Raspberry Pi?

“The Raspberry Pi is a credit-card sized computer that plugs into your TV and a keyboard. It’s a capable little PC which can be used for many of the things that your desktop PC does, like spreadsheets, word-processing and games. It also plays high-definition video. We want to see it being used by kids all over the world to learn programming.”(http://www.raspberrypi.org/faqs)

In more detail

• ARM-based SoC with plenty of I/O• 700 MHz ARM11 core• 256 / 512 MB RAM

• Low cost - $25 / $35

The thought experiment

• Could you build a cloud using a cluster of Raspberry Pis, instead of virtualized PCs?

• Is the performance comparable?• Is the cost comparable?• Is it technically possible?

Performance

• Amazon EC2 offers “t1.micro” instances

• Conclusion: slightly inferior

EC2 t1.micro Raspberry Pi

Processor – normal Undisclosed 700 MHz single core

Processor – spiked 2 ECU single core(ECU approx equivalent to 2x 1GHz 2007 era Xeon)

700 MHz single core

Memory 0.615 GB 0.5 GB

Costs

• Model B Raspberry Pi is $35• Scientific researcher built a 32-core cluster

using Raspberry Pis for $1967.21

Costs

• Dell PowerEdge R520 for $2759– List price – discounts almost certainly available

• Intel® Xeon® E5-2440 – 6-cores @ 2.4GHz• 16GB memory, 500GB hard drive• Compared to the Raspberry Pi cluster:– Same RAM– Equivalent to a 16GB SD card in each Pi– 6x 2.4 GHz = 14.4, versus 32x 0.7 GHz= 22.4

Technical issues

• There’s no virtualization, no hypervisor, no PXE boot – just an SD-card based bootloader

• How could we provision the user’s required image automatically?

Technical issues

• A “bootstrap” OS• Starts on Pi reboot• Erases all data on the user partition• Clones the OS image from network storage• Re-boots into the user’s OS

Summary

• Performance – comparable with an EC2 t1.micro

• Cost – 32-core cluster comparable with a heavy-duty PC

• Technical – some issues but it is feasible

Conclusion

• It’s not a completely ridiculous idea!• But this is only a thought experiment…• Not considered:– Physical rack mounting– Network switch port demands– Thermal requirements– Power consumption and distribution– Reliability and lifetime of a Raspberry Pi

References

• Raspberry Pi official website: http://www.raspberrypi.org/

• US boffin builds 32-way Raspberry Pi cluster: http://www.theregister.co.uk/2013/05/20/32_way_raspebrry_pi_cluster/

• Dell PowerEdge R520http://www.dell.com/us/business/p/poweredge-r520/fs

• Intel® Xeon® Processor E5-2440: http://ark.intel.com/products/64612/

Addendum

• The University of Glasgow’sRaspberry Pi Project: http://raspberrypicloud.wordpress.com/

(thanks to Matthew Broadbent for bringing this project to my attention)