Today I'll deal with what can be oversubscribed.
What can be oversubscribed?
•
CPUs
•
Memory
•
Disk
•
NICs
In
our virtual world, now that we have broken the link between the OS and the
hardware, we can over provision all sorts of things.
CPU,
Memory, Disk (as we mentioned) and NICs are all “Oversubscribed”.
Disk
we have already looked at, Memory and CPU I’ll go into in more detail on later but
I thought it was worth mentioning NICs here.
Typically
people seem to be running with 10 - 15 VMs on a single host which will have
significantly fewer NICs installed. A Server typically wouldn’t use all the
bandwidth of its NIC so that unused bandwidth is like the unused space on disk.
When
the VMs talk to other VMs on the same Host that’s not generating traffic though
the physical NICs, so we might consider that as the equivalent of
de-duplication.
In the next few blogs I'll be looking at CPU and Memory.
Phil Bell
Consultant
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