Is memory overcommit a problem on VI3 using Linux guests

[johnny99]

Hi

Does anyon know of memory overcommit is a problem om VI3 when running Linux guests?

I have seen tests that seem to show that the memory is used totally different then when guests are Windows.

Has anyone an explanation to this situation I see?

/johnny

 

[Arisap]

I can at least say this. I am running a 4 node cluster of DL585G2's with 4 Dual Core Proc's and 32GB RAM. The cluster therefore has 83GHz and 127GB of RAM available. We are using DRS to load manage at "Fully Aggressive" We are running 107 VM sessions -- 22 RHEL3, 79 RHEL4 and 6 RHEL5. The memory to each ranges between 1024MB and 4096MB for a total of 225,264MB of RAM. So, in short, we are running 225GB of RAM on 127GB Physical RAM. Things are runing great very well. Granted these are all developmet sessions

 

[johnny99]

What database systems are you using?

Some of ours are Oracle some MySQL in the guests.

Could the databasesystems be the real source of the problem.

All Linux Are RHEL5, some 32 bit, some 64 bit.

I am new to the project, but from the short problem desc. I got it sounded like ones many years ago I worked together with someone who forgot to install the VMware tools on the Windows guests and VMware started to page the guests out.

We will have a new meeting in this week and I hope to get more info then.

What is so strange to me is that this should be so easy and then we have this type of problems.

The people setting up our VMware and Linux have done this a ton of times before and I don't even know how many servers we have running VMware and Linux. And this problem has never been seen before.

/johnny

 

[Arisap]

What exactly is the problem? you didnt state it in your original posting.

I really don't know what applications or databases are running on those Linux guests, but my guess is: everything you can imagine. Installing VMware Tools is VERY important for all guest OS's for a variety of reasons.

 

[johnny99]

The problem is that the same second we define more memory to the guests then there is in the server some of the guests start to perform very very poor.
And we have seen guests that stop to respont for up to 20-30 min.
As if the guest(s) are swapped out.

And we only see the problems on Linux guests

/johnny

 

[johnny99]

An update.

It seems as if we get the problem as soon as we have guests running that have defined more the 4 GB of memory.

In test we can get the guests to run fine as long as we don't have any guests running with more then 4 GB memory.

/johnny