Over-allocating memory for VM guests
Posted on 2010-09-05
I had a query on VMWare ESX 3.5 I was hoping someone could help me with. The questions surrounds memory usage.
Let's say the ESX host has 16GB RAM.
I have four guests running on it, each with 4GB RAM assigned. Technically, this should be fine I understand, because the servers won't always be using 4GB RAM, and even if they did, then we are covered.
Now, let's say I added another guest with 4GB RAM. Even if we don't expect the all servers to use their full memory allocation at the same time, can this still cause performance degradation to the host (and therefore other guests)?
In general, what are people's recommendations in terms of allocated RAM v physical RAM?