Memory ballooning alerts

[Guv]

We are using vsphere 4.1. We are also using SCOM 2007 to moinitor performance of our VM's. We are using the Veeam managemnt (nworks) for vmware. I dont know if many people have used this and what their feedback is.

Anyways in SCOM we are getting many alerts regarding VM Balloon Memory Usage has exceeded threshold, and VMGuest has exceeded threshold for memoryCtl (balloon memory) for some specific VM's.

I am trying to understand what ballooning does. Does this alert mean the memory has been taken away from this VM for other VM's, and now this VM does not have enough memory, or is it saying that this VM is borrowing too much memory from other VM's.

Can anyone advise what VM ballooning actually means and what this alert might refer to.

Can a VM lose memory due to memory been taken for other VM's (ballooning) which then affects its performance. Any advise.

[AWo]

If you have assigned more memory to the guests than the host has physical RAM or if you have applied a memory restriction to a guest ESX has some mechanisms to server memory requirements if a guest needs more memory, which is not available.

The first thing it does is it expands the balloon driver in the memory one guest, forcing that one to swap out to its disk (guest swapping) because the balloon driver requests RAM. That RAM is then cut off from this guest and granted to another guest which has requested memory to use it actively.

If that is not enough ESX starts to emulate RAM for individual guests, but swapping out guest memory to ESX datastores (host swapping).

Both situation shouldn't occur if you have more or at least an equal amount of memeory as you have assigned to all guests in total.

Both situations slow down the processing.

AWo

VCP 3 & 4

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