VM guests and memory usage

[handers101]

Hi

I would just like someone to clarify a point regarding memory in esx.

I have a VM with 2GB of memory, no reservation set (therefore a 2GB swap file), no limits set either. (although i have read that when i set the 2GB then this is the upper limit?)

I have followed Microsoft best practice and set the page file to be 1.5X the physical memory.

I have read all the documentation regarding memory articles that have been refered to on other posts.

My issue is the when the virtual machine exceeds this 2GB of memory, the host os pages, Vmware performance counters show that the machine was only using 40% of its memory used.

Why would vmware report a low value for memory used when the machine has run out of physical memory and is paging?

If anyone could offer any advice, i just need to get this straight in my mind.

Thanks

[RParker]

The counters don't show you the guest usage, only the memory allocated by the host. So yes, the host may only need to give 40% of it's memory to allocate 2G RAM to a guest. This is normal.

The performance counters can't actually get the real picture, for that you need something like vizioncore performance monitor to track the VM usage.

[handers101]

Hi Thanks for that

I have just had a quick look and is it vCharter?

Looks like i need some performace monitor for the VM's, any idea how much vCharter costs (roughly) and can you download a demo?

Thanks again

[RParker]

It's licensed per socket, so if you monitor a host and it's a dual quad/dual core, that's a license.

I can't remember exactly, we buy ours as part of the essentials pack which includes charter, backup, and replicator, and that is roughly $1500.00 per host. I believe vcharter is something like $350.00 per server ($175 per socket) but that's a guess, I can't remember. I just know it was cheaper to go the essentials route which includes those 3 products. We really don't use replicator yet, but we bought it because we wanted vcharter and vranger, and it less expensive to include replicator as part of the suite.

Yes you can download a demo from the page, however they are in the process of coming out with vcharter pro (who knows when) and you can't download for the moment until the new version is out.

[Eyad]

How are you reading the counters, in virtual center, the console or via a third party vendor?

[weinstein5]

1) With no limit set - the available memory (memory set when vm is created) becomes uppper limit

2) The VMkernel utilizes Transparent Page Sharing - the ability to recognized memory pages that are identical and will store them one time - so in your case the VMkernel has consolidated memory but to the Guest O/S still sees it is using 100% of the 2 GB thus neccessitating the use of the pagefile - while in reality the VMkernel is only using a fratcion of that in physical RAM to store the VM memory contents -