Memory Ballooning in ESXi 4.0 Host

[KrishK]

I recently observe my VM's (Citrix) performing poorly for about 15 mins everyday at particular time. Upon alalyzing from VMware perspective i could see a Memory Ballooning and Disk Write spike of both VM's and ESXi 4 host in performance chart at the same time. Can this be a source for the VM slowness?

Suggestions and Solutions are most appreciated.

Thanks,

Krish

[Dave_Mishchenko]

When your host runs low on memory ESXi uses the memory balloon driver within the guest OS to force it to use its own paging system and thus free up memory that the host can use.  The use of the balloon driver will subsequent lead to increased disk I/O as the guest OS pages low priority memory to disk. Is something else happening on the host during this period?  You might consider a memory reservation for the Citrix VMs, but it may be that the host requires a memory upgrade.

[KrishK]

Hi Dave...Thanks for the time..

I don't see any memory crunches in the ESX box...Its just using 75% of the total Memory available but this is happening everyday at same time say 11AM. I can still try having a resource pool for my Citrix VM's.. Will there be any other possibilities??

Thanks

Krish

[Dave_Mishchenko]

ESXi will kick in the balloon driver before it runs out of memory to ensure that it has capacity to start other VMs.  Do you have anything scheduled in another VM type that might be creating the load?  Have you tried a memory reservation for your Citrix VMs?

[AWo]

Check if you have a memory restriction in place for that particular guest, where you see balloning, if you do not overcomitted the memory (that means that you have assigned more RAM to the guests as the physical host has free for guests).

AWo