A new week begins, and so does the fun with computer-systems.
As I tend to use a lot of virtualized systems, 'cause they are a lot easier to manage, I tried something new.
Firstofall I need to discrbe the Infrastructure hosting the VMs.
As I manage quite a bunch of systems, a normal VM-host doesn't supply enough power for them all, so I use a clustered version of the VM-ware ESX.
Hardware in this cluster is a bunch of HP-servers, all identical and a bunch of SAN-disks.
As I ran out of power on these systems my first try was to eliminate unused systems.
That cleared up some disk-space, but nearly no CPU or RAM consumption.
The next idea was to suspend systems, not needed during periods of the day. Such as development-servers, as they only need to run at daytime, when the developers actualy work on them.
I setup a timed schedule to suspend them late and power them up again before office-hours.
Okay, that worked.
Still I happened to have a lot of CPU and RAM usage and the system-manager for the cluster still showed warnings about them.
So I went for suspending systems, unused during the day. Like systems only needed for short amounts of time.
My idea was to suspend them via the "suspend when idle" function built into the Windows powermanagement.
That worked. CPU and RAM usage went below threshold and the cluster ran smoothly.
Until the systems happened to be needed again...
Wakeup of them was a problem. Sure hitting the "Resume"-button did work, but who wants to do this for more than a couple of systems.
Lets just put a number, do you want to resume a hundred systems, when they are needed, by hand?
So I went for the "Wake on Lan" option. This stuff actualy works quite well....
If you happen to have hardware-systems...
But you won't power those down...
In VM-Ware this is an entirly different story. WoL does work, but only if you keep the system running idle. If it does WoL works flawlessly, but blocks the CPU and RAM as if it was running full power...
WoL does not work, if the VM is suspended or even shut down.
So I am trying to figure out a way of dooing this by hand.