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4 Replies Last post: Apr 8, 2008 11:42 PM by jbbroccard

Need a light, reliable & sable version of Linux Guest OS for MRTG appliance (under 64-bit Ubuntu 6.06LTS on AMD 64 Opteron) posted: Apr 8, 2008 6:52 PM

zonex

2 posts since
Apr 8, 2008

So, nearly each hair on my head has been pulled out... and replaced.

Host OS: Ubuntu 6.06 Server (64-bit) - AMD 64-bit Opteron 1212

WHAT I WANT: I want a guest OS (linux) that will be light and easy and run apache with MRTG on it. Nothing too fancy.

PROBLEMS: If you know about MRTG, you know it uses the date() of the running OS (in this case the guest VM OS) to keep historical records of utilization graphs. Each OS I have installed has had a wild ride with the time/date function. I went so far as to run a crontab entry of ntpdate every minute. The problem with that, sometimes it would be 10 minutes (in real time) before the guest OS advanced 1 minute. Not good.

I followed all the tricks:

Change kernel boot to clock=pit
Install VMware tools and set clock sync TRUE
Disable CPUSPEED, POWERNOD, etc
Disable NTPD

I tried CentOS 5.1 (i386 & x86_64), Ubuntu 6.06 (32-bit and 64-bit); Ubuntu 7.10, Ubuntu JeOS 7.10.

All had time issues after countless reboots.

Any advice? I just want a clean MRTG appliance that I can use cleanly...

HELP!!!!!

Tags: 64bit, install, linux, performance, vmware, vmware_server, vmware_tools, x64, mrtg, clock, speed, cpu, speed, centos, ubuntu, server, error

Re: Need a light version of Linux for MRTG appliance

1. Apr 8, 2008 6:24 AM

in response to: zonex

SMB

403 posts since
Mar 14, 2006

Disable NTPD - You're having time problems and you disable this? If the VMware tools don't keep the time synced (you did install them right?) then NTP is the way to keep time correct, just like any other server.

Have you seen this doc? www.vmware.com/pdf/vmware_timekeeping.pdf
Going over this is what we used to solve time problems in one of our guests.

Re: Need a light version of Linux for MRTG appliance

2. Apr 8, 2008 6:25 AM

in response to: zonex

MaxVernon

143 posts since
Jun 15, 2006

I have an AMD Opteron server running SUSE Linux 10 which had severe and strange problems that seemed related to clocking. The only fix that worked for me was to disable all power-saving functions in the BIOS. After I did that, all guests run just as expected.

Re: Need a light version of Linux for MRTG appliance

3. Apr 8, 2008 6:50 PM

in response to: SMB

zonex

2 posts since
Apr 8, 2008

SMB wrote:Disable NTPD - You're having time problems and you disable this? If the VMware tools don't keep the time synced (you did install them right?) then NTP is the way to keep time correct, just like any other server.

Have you seen this doc? www.vmware.com/pdf/vmware_timekeeping.pdf
Going over this is what we used to solve time problems in one of our guests.

Of course we DISABLE NTP/NTPD on the guest VM... The document you suggest, which we have already applied, even agrees:

"(W32Time) or the Network Time Protocol (NTP) does not work well when run in a virtual
machine. If the virtual machine is aware that it is behind real time and is already delivering timer
interrupts at a higher rate so that the guest clock can catch up to real time, running non-VMware
clock synchronization software inside the guest at the same time may also advance the virtual
machine's clock, causing it to end up ahead of real time."

We learned this the hard way - forcing ntpdate to update out of cron every 1 minute... Problem was, system clock wouldn't advance evenly (sometimes 1 minute would take 10).

Today has proven a little better in usng the vmware-tools clock sync, killed NTPD, no powersave/bios tricks, running MRTG as a cron job (not as daemon). A few locked lags which show a bit more horizontal plateaus than I prefer (due to date/time sync offset). But, at leas it is running.

Still looking for the best, lightest OS that will run best inside a 64-bit Ubuntu 6.06LTS Server on an AMD 64-bit Opteron 1212 w/ 4GB memory....

Re: Need a light version of Linux for MRTG appliance

4. Apr 8, 2008 11:42 PM

in response to: zonex

jbbroccard

6 posts since
Apr 8, 2008

Hi,

I guess your problem is the same as mine, I just soved it here:

http://communities.vmware.com/message/909345

I think if you run a little command-lie script like this, the seconds don't last 1 second:

$ while true ; do date ; sleep 1 ; done

Check the pdf mentionend above, but unfortunately, you'll have to go through a kernel rebuild. And it's tricky if you're not familiar with Linux

BTW, I have 8 VMs running on top of Ubuntu server 7, and 4 Red Hat hosts with the issue, 4 Debian/Ubuntu running normally.

Good luck, if you need tips to recompile, do not hesitate

JB

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