I am building a new production environment and I have been thinking whether I should use 32bit or 64bit Debian 7. All the servers will have less than 4Gb of memory so I thought I could save some memory by using 32bit Debian.

Then I started thinking if 32bit Debian has worse package availability. Does it? Any other things to consider?


The Debian buildd stats show that, at least on Intel or AMD-based PC platforms, the coverage is pretty much identical. (The stats cover unstable rather than Wheezy.) You'll find some 32-bit-only packages, and some 64-bit-only packages, but they are few and far between.

Will a 32-bit linux OS work on modern desktops that are compatible with 64-bit? considers the performance aspects; on the same, 64-bit-capable system, 64-bit code is often faster than 32-bit code, not because of the size of the instructions, but because the instruction set is more capable (in particular it has more registers).

So if you go for 32-bit Debian, you shouldn't come across packages which you can't install, and you will save some memory, but you'll lose some performance. You can get the best of both worlds though by installing 32-bit Debian with a 64-bit kernel (the amd64 kernel flavours which are available as 32-bit packages); that way you keep the memory savings, you get better performance in the kernel, and you can run 64-bit software using multiarch if necessary.


Packages are available for nearly every platform, 32bit certainly has great coverage.

The only thing you may wish to consider is that it may be faster to send 64bit instructions to the CPU then to send 32bit padded instructions to the CPU. But this depends a lot on your setup. Usually virtual machines should try to be the same as their host hardware. Real machines are less important, but could still be a factor.

Using 64bit will not consume "that much" extra ram, though, so the question is, are you over thinking a problem that you don't have.

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