Guest Memory Allocation

[bmwbadboy]

I am running 4.1 U 3 esxi.  I have several Windows 2003 servers 64 bit, that we had assigned 8Gb of memory. They are all running Citrix Xen App 5. We have published a Medical Practice Management client app called Pulse Systems. After checking esxtop, touched memory and checking the memory usage over the past month inside performance charts the server never touched or used more than 2Gb of memory.  Last night I reduced the memory on the Citrix servers to 3GB.  This morning as our users started to login we began to receive calls because the users were getting memory errors.  So we had to bump the memory back up to 6GB.  My question is I thought we could tune memory by looking at the actual performance of the vm guest?  It seems that in actual practice we have to tune it by what gives the application enough memory to run usefully.  Anybody have any thoughts about this?  Any other way to tune memory?

I've posted some screen shots, Windows is using up all the memory, but touched memory is less than 2Gb. The last month memory use is an average of 7.5% of granted, which was 8Gb. We updated the memory to 6Gb this morning, and now just added another 1Gb so we are at 7Gb.

[Linjo]

The performance charts is normalized after time and will not show any peaks in utilisation.

If you where not on an old esx-version I would recommend to look at vCenter Operations instead, there is a 60day trial to download

// Linjo

[depping]

One thing to note is that we are not talking about "uniquely touched pages" here. The 2GB that is touched now could be 1.8GB different from the 2GB that was touched an hour ago. So even though it "looks" the same, it doesn't mean it is... leading to swapping when you reduce the size of memory.

[BrownUK]

This statistic is a bit misleading, you only ACTIVELY touch 2GB of memory in some period of time, what you are touching may change over time.

Also your server may allocate a lot more memory to run that it is touching, but if it needs it this becomes available.

Look on the resource allocation of a Virtual Machine at the Unaccessedfigure, it may help

Thanks

Alastair Brown|Microsoft Engineer / Vsphere Architect| Produban UK Commercial

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