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sjoerdhooft
Contributor
Contributor

VMs have memory limit set

Hey everyone,

I have a strange issue on my hands. We recently upgraded to a 5.1 environment and moved al our hosts to a new 5.1 vCenter. We decided we didn't need any information or history from the old environment and that decision now comes back to hunt me...

Last week I noticed some new VMs to have a memory limit. Luckily it was set to the same amount of the configured memory so no harm done. I found out about it because there were performance issues on some servers that were scaled with not enough memory and a change was already been approved to increase the amount of memory. Luckily I was standing with the system administrator who was working on the VMs so I could tell him to remove the limit before increasing the memory.

Of course, the system administrator (a different one) who created the VMs denies setting the limits. I'm right now busy running a script to find out which VMs have a limit set. I removed all limits on all VMs about one year ago, I'm totally sure about that, I even found the change in the tracking system. Strangely enough it looks like almost every VM has a limit set. That's weird because I believe that something like that can only be done manually (or scripted).

Does anyknow know of a scenario in which a memory limit could be set by accident? For instance when upgrading to vSphere 5.1, or using update manager to update VMware Tools or virtual hardware.

Removing the limit is easily done, so I'm not interested in that. Just trying to find out what could have happened. I'd appreciate every input!

Thanks in advance!

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DyJohnnY
Enthusiast
Enthusiast

Hi,

I have had the exact same scenario happen to me, moments ago.

We run 2 vcenter instances right now, one is v4.0 and the other one is the new vcenter 5.1.

After we setup vcenter 5.1 we started migrating each host one by one to be managed by this new instance. So we disconnected the hosts from v4.0 and added to v.5.1.

Today I just discovered that some of our Vms were doing some sort of swapping (we had actually hit a vsphere DRS bug). So i manually balanced the hosts in the cluster, but the Vms still showed swappping to occur.

After digging a while I discoverd all our running virtual machines from the migrated hosts had memory limits set. All of them.

Having the old vcenter up and running I went and checked whether they had limits in the old environment, guess what, they had no limits. so it wasn't any setting that translated over.

I looked in the events for a few VMs in vcenter 5.1 logs, none of them have the task/event "reconfigure virtual machine" which is the name of the task when someone changes this manually/scripted. The only event was the event when I removed the limits.

So, I'm not sure your systems administrators are to blame, from the troubleshooting we have done, these limits must have been set when you added the host to the new vCenter. We know this because after moving your 4.x hosts to v5.1 vcenter, we upgraded SOME of the hosts to 5.1. But since we still had 4.x hosts and all our VMs have limits, it is clearly not because of the some bug in the upgraded host.

I hope this helps,

IonutN
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jdptechnc
Expert
Expert

I, too, have noticed this behavior.  I created a new vCenter 5.1 server, and moved all of the hosts to it.

In my case, there had been limits set in the 4.1 envrionment set by a previous administrator.  Months ago, I ticked the box to set all of the machines with lmiits to unlimited.  After I attached the hosts to vCenter 5.1, all of the machines that previously had limits had the same limits as before.  I think it's a bug.  The machine must have still had the old memory/cpu limit value in the config file, and when it attached to vCenter 5.1, it started using the old value and ignored the fact that "unlimited" was checked.

Please consider marking as "helpful", if you find this post useful. Thanks!... IT Guy since 12/2000... Virtual since 10/2006... VCAP-DCA #2222
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