The thing to keep in mind is that the move to 64bit will inherently use more memory, because the OS is designed with that philosophy in mind. It's pretty much assumed that if you are running 64bit you likely have 4GB or more RAM as that is one of the key reasons why you would move to 64bit (the fact that 32bit OS can't address more than 4GB). You can of course run with less than 4GB of memory, but you start to put unnecessary constraints on your system by doing so.

 

This is predominantly true in the Windows world, and while likely less of a concern in Linux it's still applicable.

 

Additionally, given the prices of ram the argument on 1GB vs 2GB vs 4GB seems somewhat silly. If we were talking the difference between $50 and $100 or $200 then sure, but it's basically a $10-20 difference, so I am sort of hard pressed to see the value of the argument other than for the sake of the argument itself.

OK, I googled it, and it does seem you guys are right - x64 kernel does use more memory. Estimates I have seen range from 30% to 60% more. This is the best explanation I have seen:

http://askubuntu.com/questions/7034/what-are-the-differences-between-32-bit-and-64-bit-and-which-should-i-choose

 

But Hey, with unraid we are running rather large RAM-drives, so yes OS and applications will take more, but it will partly be offset by reducing the unraid RAMdrive from (in my case) ~550MB to something more reasonable.

 

I still think it's feasible. If it's very tight, one could always use a 32-bit VM, or if more than one VM is required, some of them may be perfectly fine with 32-bit. The base requirements for console-only linux are really quite modest.

 

Ubuntu CLI requires 192MB RAM (they mention 64-bit, but don't make a distinction between 32 vs 64-bit for min. RAM):

https://help.ubuntu.com/community/Installation/SystemRequirements

 

Slackware requires 64MB. No, not GB - MB (no mention of 64-bit at all, so assume that is for 32-bit only):

http://www.slackware.com/install/sysreq.php

 

Apps like Subsonic, sickbeard, couchpotato, Transmission and NZBget take very little RAM and adding on an extra 60% would be a non-issue.

 

SabNZB would be a problem, but I don't see any reason to go back, NZBget is really good these days.

 

Lastly, if one were to assign a VM with RAM on the tight side of things, and a swap file, that swapfile would be cached by the host VM, so it wouldn't slow down the VM to the same degree as a physical OS using swap.

 

With fear of repeating myself, it is not primarily the monetary expense of adding RAM that concerns me, it's the need to validate stability that will take time and cause downtime. Going from 2 to 4 modules is not without risk, for example. Also, I don't own a monitor for my unraid box, and it has become too heavy to carry upstairs ;-) The fact that DDR2 ram is 50-70% more expensive than DDR3, and that I wouldn't be able to reuse DDR2 in a future DDR3 system is a minor concern as well. Sometimes less is more.

A new MB with DDR3 RAM can be cheaper than buying DDR2 RAM for an old MB.

A new MB with DDR3 RAM can be cheaper than buying DDR2 RAM for an old MB.

 

I've been on the cusp of just this decision myself to get more then 4gb for when i go VM

All systems I build these days have a pair of 8GB modules ... 16GB total ... "just because".    Remember that with unbuffered modules, it's MUCH more reliable to only install 2 modules -- so I want to be sure I use high enough capacity modules that I don't end up tossing them (i.e. selling on e-bay) to replace them with larger modules.

 

I think 16GB is plenty of "headroom" for anything I might want to do in the foreseeable future ... and it certainly doesn't hurt to have "too much" RAM    [it does, of course, add a tiny bit of extra power consumption & a few $$ of extra cost]

A new MB with DDR3 RAM can be cheaper than buying DDR2 RAM for an old MB.

Ain't that a sad truth...weird but true.