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Being unfamiliar with how one creates a Linux distro, can you go into a little more detail as to the difference between targeting virtual hardware over physical

Being unfamiliar with how one creates a Linux distro, can you go into a little more detail as to the difference between targeting virtual hardware over physical hardware?

philips 13y ago
Sure! There are a few differences: 1) Installation: On physical hardware you need to provide a way for people to initially boot and then install the software on disk. Sophisticated people want something they can boot over the network and script. Everyone that is just trying it out wants a GUI; which means you have to build something that finds disks, helps the user partition them and installs the software. On virtual hardware there is usually no install step: you just get a VM image and run it. This lowers the barrier to people trying something out. 2) Hardware support complexity: Physical hardware has hundreds of different devices that come in thousands of different combinations. Some of it requires 3rd party drivers and custom configuration at boot time. Supporting everything ever made adds a lot of complexity. I think it is a bit comparable to the complexity that ORMs have of running on top of 20 different databases and still providing a useable interface that doesn't break. In the virtual hardware space there are only about 4 sets of Kernel drivers that you need to support all of them and they are generally well tested. 3) Test cycles: It is easy to turn on and off virtual machines for testing and the developer feedback loop is tight for even the tricky bits like our boot code (>60s). However, on physical gear it can take 5+ minutes to test out a single iteration because of copying over the new binaries, slow booting disks, etc. 4) Customer debug cycles: Without easy access to the same physical hardware a user has I have to build a debug image, have them install it, then give me the debug output. This cycle can take days. Something like the Open Compute hardware can reduce a lot of these pain points. Also, in a given year a majority of servers have similar hardware so you can work on a lot of gear with minimal additions if you curate.

Being unfamiliar with how one creates a Linux distro, can you go into a little more detail as to the difference between targeting virtual hardware over physical hardware?

philips 13y ago

Sure! There are a few differences: 1) Installation: On physical hardware you need to provide a way for people to initially boot and then install the software on disk. Sophisticated people want something they can boot over the network and script. Everyone that is just trying it out wants a GUI; which means you have to build something that finds disks, helps the user partition them and installs the software. On virtual hardware there is usually no install step: you just get a VM image and run it. This lowers the barrier to people trying something out. 2) Hardware support complexity: Physical hardware has hundreds of different devices that come in thousands of different combinations. Some of it requires 3rd party drivers and custom configuration at boot time. Supporting everything ever made adds a lot of complexity. I think it is a bit comparable to the complexity that ORMs have of running on top of 20 different databases and still providing a useable interface that doesn't break. In the virtual hardware space there are only about 4 sets of Kernel drivers that you need to support all of them and they are generally well tested. 3) Test cycles: It is easy to turn on and off virtual machines for testing and the developer feedback loop is tight for even the tricky bits like our boot code (>60s). However, on physical gear it can take 5+ minutes to test out a single iteration because of copying over the new binaries, slow booting disks, etc. 4) Customer debug cycles: Without easy access to the same physical hardware a user has I have to build a debug image, have them install it, then give me the debug output. This cycle can take days. Something like the Open Compute hardware can reduce a lot of these pain points. Also, in a given year a majority of servers have similar hardware so you can work on a lot of gear with minimal additions if you curate.