VMKERNAL Heap

[epj]

I upgraded to the new vCharterPro and while looking over all the new features I noticed that it stated the followinf about all my hosts:

"The amount of free memory in the vmkernal for ESX Server xxx.xx.xx.xxx is running low. Only 8271.0 KB of free heap memory remains."

looking at the individual hosts all show the same numbers 30MB for the heap and 8271.0 KB free. Currently we are running 4 servers in a DRS/HA cluster and one floater out side the cluster for testing and general use. We have only 44 server total at the moment as we are migrating over VM's as time will allow from our old farm.

Anyway question is what setting (if any can I change to increast the heap for these machines? all hosts have 32GB of ram installed.

I found one setting that says COW heap and its set at 32 currently but I was unsure if that was what I should be changing??

We are running 3.5.0,82663 across the board.....

Thanks for any info that could be shed on this....

Ed

[Ken_Cline]

Last time I heard of issues with the vmkernel heap, it was because of Broadcom pNICs. The Broadcom NICs use more heap space than Intel NICs (or they used to...), which could cause a warning to be issued.

Ken Cline

Technical Director, Virtualization

Wells Landers

VMware Communities User Moderator

[beckhamk]

did you ever get anymore info on this from vmware?

[epj]

Not really, I did a lot of FAQ searching and all of this appears to be mostly related to 3.01 more then 3.5

The only reason I even knew about the possible issue was that VcharterPRO calls it out as an issue. So far though none of my server (5) have changed the heap size since deployment. In other words they have not reduced in size at this time.

We have moved over 50+ Production machines from the old farm and still have another 25 or so to move. So I will be watching the heap size to see if it changes.

I'm just wondering if it is something I need to even pay attention to under 3.5??????

Thanks

[A_Knight]

i have the exact same issue, also only noticed since vcharter pro was installed. I haven't found any way of fixing this, has anybody else?

[Ken_Cline]

I would suggest opening a support case with Vizioncore and ask them directly what is the meaning of the warning - and what is the risk.

Ken Cline

Technical Director, Virtualization

Wells Landers

VMware Communities User Moderator

[Brucealeg]

I have ESX 2.5.2 servers that are down to 3.6MB of heap. I've worked with Vmware extensively with this as low heap can cause ESX servers to disconnect from Virtual Center and of course zero heap and you crash. I was told ESX 3 uses the heap much more efficiently and there should not be an issue. I was also told we could increase the size to 64MB, to be sure, but no one has supplied me with a command to do so.

Bruce

[bretti]

Hello,

I opened a case with VMware regarding the heap size free amount being so small. The way I understand the answer I got from VMware is that 3.5 handles heap size different than 3.0.x. Here are some notes from the support case with VMware. It seems to be a non issue as far as ESX is concerned. I think the warning threshold for vCharter Pro just needs to be adjusted to take into account the changes with 3.5 heap size. You can adjust that value in vCharter Pro in "Administration / Rules & Notifications / Manage Registry Variables / VMW:serverFreeHeapMemory.critical" The default value is 10240.0. I changed it to 8000.0, and the alarms stopped triggering.

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VMware SUPPORT:

Has this caused any errors? I double checked my lab servers /proc/vmware/mem file and saw close to the same.

I confirmed this with two senior coworkers and they do not recommend making changes to the ESX heap. Changing this setting could make your server unsupported. Note the file you viewed only relates to the ESX services and not any guest hosts. Any guest OS you install on the guest server will have their own system heap.

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VMware SUPPORT:

Yes you will see memory usage differences between ESX 3.5.0 and 3.0.1. The default values are the optimum for default ESX server installs. Unless you are making additions to the ESX server portion of the server you should not need to make changes to the heap. Your OS and Application will be running in a separate memory space in their Guest host spaces. They should not impact the heap. If it is OK with you I would like to close this ticket as you are not seeing any issues at this time. Should an issue arise, please contact us.

[A_Knight]

I've had the saem issue with vCharter Pro and ESX 3.5 and after discussions with colleagues and looking at other sources decided toadjust the thresholds within vCharter Pro rather than mess about with the heap sizes with ESX. After all there seems to be no issue as far as ESX is concerned.

Regards

Andy.

[b18b]

Hi,

We've got the alert showing on all 3 of our ESX 3.5 U 3 hosts showing in Vfoglight

The amount of free memory in the vmkernel for ESX Server esx01.intranet.x..au is running low. Only 7666.00 KB of free heap memory remains.

Found the following VMware KB article

"The default heap size for VMFS-3 is set to 16Mb. This allows for a maximum of 4Tb of open virtual disk capacity on a single ESX host. "

We are currently approching 4TB of storage, so we're not sure if we should increase this memory setting.

Also found information on the following link suggesting increasing the console memory to 800Mb from standard:

Anyone had to do any of the above?

Cheers

[Rubeck]

"Diagnosing Vision Core's vfoglight console memory heap error"

http://kb.vmware.com/selfservice/viewContent.do?externalId=1007256&sliceId=1

/Rubeck