Submitted by clwheatley on Tue, 12/29/2009 - 10:10
We've recently installed 8 GB of memory into two of our VM servers (one live and the other a hot swap). After re-boot the system only recognized 3.5 GB and from what I have been able to find in the forums is that to allow the remaining memory to be used we only need to install the bigmem kernel.
Is this all that is necessary? And presumably this will cause no issues with Virtualmin, correct? Or is there a different method you suggest?
Thanks,
Chris
Status:
Closed (fixed)
Comments
Submitted by andreychek on Tue, 12/29/2009 - 10:22 Comment #1
Howdy -- yeah, the bigmem kernel should do the trick.
I suspect what you have is a 32bit i386/i686 install, which would only be able to see a limited amount of RAM.
The ways to solve that are:
Install a 64bit distro, which can see all your RAM out of the box.
Install a kernel with PAE enabled, which is a feature that enables 32bit systems to see all of your RAM. That's what the bigmem kernel has. You can read more about the PAE mode here:
http://en.wikipedia.org/wiki/Physical_Address_Extension
Either of the above options will work just fine with Virtualmin.
Submitted by clwheatley on Tue, 12/29/2009 - 12:50 Comment #2
Actually both systems are 64-bit. Would the bigmem kernel still apply in this environment?
Submitted by andreychek on Tue, 12/29/2009 - 12:54 Comment #3
Hmm, what does the command "uname -a" on there show?
Submitted by clwheatley on Tue, 12/29/2009 - 15:52 Comment #4
UNAME results:
Server1: Linux lamphost1 2.6.18-6-686 #1 SMP Mon Oct 13 16:13:09 UTC 2008 i686 GNU/Linux
Server2: Linux lamphost2 2.6.26-2-686 #1 SMP Wed Nov 4 20:45:37 UTC 2009 i686 GNU/Linux
Submitted by andreychek on Tue, 12/29/2009 - 22:55 Comment #5
Yeah, the 686 there indicates a 32bit kernel. So although you have 64bit hardware, you have a 32bit distro, or at least 32bit kernel, installed there.
For Debian, if you want to use a 64bit distro, you'd want to use the amd64 release (which works for 64 bit Intel or AMD).
Submitted by clwheatley on Wed, 12/30/2009 - 09:28 Comment #6
Ok, then my options are either to install the 64-bit kernel or the 32-bit bigmem kernel, correct?
Should I choose to go the 64-bit route, will that affect Virtualmin and/or Webmin in any way? Would they need to be updated to 64-bit versions as well?
Chris
Submitted by andreychek on Wed, 12/30/2009 - 12:52 Comment #7
Well, I believe you choices are:
It sounds like you're using a 32bit distro, you could just use the bigmem kernel
Reinstall the OS, and install using a 64bit distro
In your case, I may be inclined to keep things simple and go with the 32bit that you have now, and just use the bigmem kernel -- but you'd need to weight the benefits and drawbacks of each (for performance, memory usage, special apps you have that may not work on one or the other, and so forth).
Regarding Virtualmin specifically -- the core Virtualmin code doesn't care either way. It's just Perl code, which makes it largely indifferent to platform/architecture.
As for dependencies and such -- there are distros that are supported better than others. But again, 64bit stuff is pretty prevalent today, you shouldn't have a problem either way with Debian. You can see here that both the 32bit and 64bit Debian versions are considered Grade A Supported by Virtualmin:
http://www.virtualmin.com/os-support
Submitted by clwheatley on Tue, 02/02/2010 - 18:11 Comment #8
Recompiling the kernel for 64-bit was all that was necessary. We experienced no problems whatsoever. The whole process took a good amount of planning and we were down for about a minute.
The only hitch was a problem with Postgrey afterwards. Email was being received but went no further than Postgrey. We ultimately had to unstall it and then reinstall it.
Chris