Problem with Windows 7 memory usage - again

[biokovo]

I have already wrote about this "problem" but without any answer, so I will ask again

We have 10-15 Win7x32 VMs on 3 esx4 hosts in cluster.

In Task Manager->Performance on any of that VMs there is about 1-1.5 GB memory used, but in vCenter Cluster->Virtual Machines there is about twice memory (3 GB) consumed by host for that VM?

Thanks on any opinion.

[ChaimZ]

Hi Biokovo,

How much RAM is provisioned per VM?

[biokovo]

Hi.

Some are 2GB and some are 4GB.

[ChaimZ]

Thanks.

Ok, so from what I understand, you are saying that the machine is provisioned for either 2GB or 4GB.

In Windows 7, TM is saying that the memory used is 1.5GB (max).

In vCenter it is showing consumed around 3GB.

What heading is that under? Host Mem - MB or Memory Size?

Also, what is the Guest Mem - % showing?

Maybe a screenshot will help?

[biokovo]

I can't beleive, now the situation is almost ok?! I don't know why, I tried something last night but I don't think that was important for this.

The screenshoots are here. And points for help

Anyway in the screenshots you see there is a different between memory consumed on win7 (1,96 GB) and on the host (2,755GB)? Before it was 1,96GB and 3,5GB.

[ChaimZ]

Thanks for the screenshots!

Ok, from what I understand, when you boot up a Windows machine, most, if not all of the memory is consumed. That means that all of the pages are assigned or mapped from the Guests table to the physical hosts page table. As the system stays up, the actual memory in use by the Guest and reported by vCenter or ESXTOP is stabalized. If you look to the right of 2775, it shows that system only using only 23% of the total RAM provisioned.

You can see this better (IMO) by running ESXTOP on the console or by RESXTOP from vMA. The TCHD column shows you that the system is not really using all of the RAM provisioned to hit but rather (in your case) 1.9GB or close to it.

I hope that helps!

[biokovo]

Thanks.

But if it is true, why 23%? 1,96GB of 4GB provisioned memory is about 50%.

And another fact, when the sum of consumed host memory (this 2,755GB and other) is near of total physical memory I must power on another server becouse of bad performance of that VMs. Vmware power managament will not automatically power on another server probably becouse sum of really consumed memory is bellow critical and it thinsk thats everything is ok, but it is not.

Another questions is why I can't give you a points? Something problem on forum?

[ChaimZ]

I believe that the answer to the memory question is because the host server has to "poll" the area of memory being used by the system. The number will become more accurate over time. I tested this on one of my Windows 7 systems. I sat there looking at the numbers (of course doing other work) and eventually the numbesr actually matched up. I then opened a IE 7 window with about 8 tabs. The RAM shot up in usage. When I closed it out, the numbers - over a period of time - sync'd up or were pretty close. Its not an instant % for you because the host does not know about it since it does not know whats going on in the Guest.

What I've done on our 3 ESX servers is look at how much peak RAM each VM is using. I then lowered the RAM to a little above the peak.

For example, we have a VM that was assigned 4GB of RAM. I noticed that the peak usage was 1.8GB over a span of time. I lowered the RAM value to the VM to 2GB. I saved about 20GB of RAM this way and now only use 2 of the 3 servers. One is dedicated as an HA host.

As for the points, I have no idea. But thanks anyway! I hope I helped.

[biokovo]

Thanks a lot on kindly answers.

Best regards,

Ante