As we know, the source code for Android 4.0 "Ice Cream Sandwich" is going to be published fairly soon, which means developers of all trades will be able to download, modify, and compile it into ROMs. A few great examples of this are handset manufacturers (SE, Motorola, HTC, etc) working on incorporating ICS into new and existing devices as well as CyanogenMod developers merging the source with all the awesome modifications they've added into CM so far.

Have you ever wondered what it takes these people to build the Android source? I never really gave it too much thought, but whoa - never in a million years did I think that building ICS would take these kinds of resources (according to JBQ, a Google developer working on Android):

ICS will be a much larger release than any previous Android release. That means that it will also put a much bigger strain on the machines that people use to compile it. As a rule of thumb, everything about ICS in AOSP will be about twice as large as it was for Gingerbread.

Here are some preliminary numbers. Final numbers will probably be a bit different, but those should be a reasonable first-order
approximation. Of course, your mileage may vary.

  • 6GB of download.
  • 25GB disk space to do a single build.
  • 80GB disk space to build all AOSP configs at the same time.
  • 16GB RAM recommended, more preferred, anything less will measurably
    benefit from using an SSD.
  • 5+ hours of CPU time for a single build, 25+ minutes of wall time, as
    measured on my workstation (dual-E5620 i.e. 2x quad-core 2.4GHz HT,
    with 24GB of RAM, no SSD).

Naturally, if you plan to work on multiple branches (e.g. ICS release, ICS development branch and AOSP master branch), you need to plan for disk space accordingly, and you could easily end up using 250+GB.

Wow... Time to upgrade your build boxes, gentlemen - this thing is a beast.

Source: Google Groups