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VMWare 6 performance problems

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Last Modified: 2018-12-09
I have a physical HP DL 380 G7 server 80 GB of memory, 900 GB storage, 1 CPU (Processor cores per socket 4 and total logical processors 8, with hyperthreading enabled).

Every client (5 guest in total) are working via their own terminal server, connected via a remote desktop gateway and asa 5510 firewall on their own vlan. OS is WIN 2008 r2,VMWare version is V6, with latest HP servicepacks on it.

Memory total is 26 GB used

Harddiskspace used is 576 GB

I gave all the guests a total of (vsocket x cores per socket =) 14 VCPU. But as i can see i have only 8 VCPU available, so am I overprovisoning?

My clients are complaining about peformance and freezing of the Remote desktop they run on. I can also see it sometimes. The screen stops, my ping times are rising to 15-25 ms in 2 seconds and than it disappears again and they can work. (i did this from a terminal server from a client and pinged the firewall and the internet).

Is this because of the over-provisioning (14 VCPU in stead of 8 VCPU available ??) does anyone has a solution or has experience with this kind of slowness in VMWare?
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Andrew Hancock (VMware vExpert PRO / EE Fellow)VMware and Virtualization Consultant
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Commented:
You’ve  allocated 14 vCPU per VM?
thisis_itIT Manager

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Commented:
Hi Andrew, no i allocated 14 VCPU in total, for all vms.
Andrew Hancock (VMware vExpert PRO / EE Fellow)VMware and Virtualization Consultant
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Commented:
How many concurrent connections per terminal server eg users
thisis_itIT Manager

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Commented:
Max. 5 concurrent connections per VM. so 25 in total via 1 remote desktop gateway to 1 terminal server (VM)
Andrew Hancock (VMware vExpert PRO / EE Fellow)VMware and Virtualization Consultant
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Commented:
Have you looked and checked performance ?

see my EE Article

HOW TO:  Performance Monitor vSphere 4.x or 5.0
andyalderretired saggar maker
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Commented:
So 7 VMs and each VM has 2 vCPU?

They can never all run at once since VMware won't let the VM run if there is only one core available since you have allocated two to it. VMware has to hold the VM until it has two free cores, and it has to suspend one of the others to get those cores free. Context switching is going to be horrific, poor old CPU has to keep dumping the registers to RAM (because the local mirror registers hyperthreading uses are already in use).
Scott SilvaNetwork Administrator
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Commented:
I agree. Over commitment is going to beat the hypervisor to death. Remember that the hypervisor also needs processor time just to run.
thisis_itIT Manager

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Commented:
Thanks; but Am i really overcommitting? Or is this normal voor VMs?
Scott SilvaNetwork Administrator
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Commented:
Also don't forget that if you have patched and upgraded the bios to the latest versions, the Spectre fixes have pretty much neutered your hyperthreaded cores...

But telling your system you have 14 cores doesn't make them exist. You don't have a system with a power chip that can virtualize partial core use. I believe Intel virtualization has to swap cores back and forth to emulate the extra cores. It would be different if all 5 vm's were not running at the same time...
thisis_itIT Manager

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Commented:
ok Scott, so what you are saying, and where i was afraid for, is that those performance issues are due to over-commitment of my vcpu.

Solution:
1) Give a vm less cpu
2) Move vms to another server


Problems with performance solved??
Andrew Hancock (VMware vExpert PRO / EE Fellow)VMware and Virtualization Consultant
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Commented:
if you turn off all the other servers, what's the performance like e.g. just one server ?
thisis_itIT Manager

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Commented:
did not try as everyone is working all day, night...
retired saggar maker
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Scott SilvaNetwork Administrator
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Adding cores would solve the issue for not a lot of money...
thisis_itIT Manager

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Commented:
Andyalder: maybe i misunderstanding from me:  when i give 1 virtual socket and 4 number of cores, i have 4 vcpus, right?
Andrew Hancock (VMware vExpert PRO / EE Fellow)VMware and Virtualization Consultant
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Commented:
yes, you have allocated 4 CPUs in the VM!
andyalderretired saggar maker
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I don't quite understand the difference between using two virtual socket single core vCPUs or using one virtual socket dual-core vCPU. In hardware there is quite a speed difference between the two but that is down to length of tracks and the speed of light. When it's virtualised there's no gain in knowing the exact differences between access speed of L1. L2. etc so keep it simple.
Scott SilvaNetwork Administrator
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Commented:
And you don't really create virtual cpu's. You are telling the hypervisor to time share the virtual cpu's with the physical cpu's on the server. So you have 4 cores and 4 hyperthreaded cores, which isn't completely equal to 8 cores since the hyperthreaded cores are linked to their real physical core...

With 14 emulated cores on your system, think of it like this... You are trying to feed 14 babies at the same time with only 8 baby bottles, and 4 of those bottles are slightly plugged up...
thisis_itIT Manager

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Commented:
Thanks for all the info and advice.

Andyalder pointed me to the solution of adding another or second CPU, which i didn't think of
andyalderretired saggar maker
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Commented:
They are dirt cheap because spare part brokers rip the old machines apart for the the motherboards which fail and get left with the CPUs which never go wrong. Two hex cores for $26, https://www.ebay.co.uk/itm/2-x-Intel-Xeon-Processor-CPU-SLBV3-X5650-12M-Cache-2-66GHz-6-Core-6-4GT-s-95w/282660571861?epid=219528039&hash=item41cfe20ad5:g:WmoAAOSwEUVbcscg

You will probably pay more for the pair of fans 496066-001 and heatsink 496064-001 plus thermal paste.

Don't forget to redistribute the RAM so half is on each CPU.
thisis_itIT Manager

Author

Commented:
Thanks Andyalder..
kevinhsiehNetwork Engineer
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Commented:
You should look at Veeam One that you can run for free. It can tell you if you are mis-allocating resources.
https://www.veeam.com/virtual-server-management-one-free.html

The issue could be assigning too many vCPU to each VM, but it sounds like you've only assigned two vCPU per VM, so that isn't horribly bad. What we haven't talked about here in the thread is your storage. What is your storage latency like? What is your storage configuration in terms of controller, cache, caching policy, RAID level, and drive types? If you're running on a pair of 7.2K SATA drives in RAID 1, or 3 drives in RAID 5, no amount of CPU is going to help you. This could be a storage problem or a CPU problem. Right now, we don't know.

I am not up on my HP server line, but I think your server is pretty darn old. Putting in two 6 core CPU is a cheap upgrade. After that, possibly time to look for a new server.

BTW, IMHO I would only deploy this going forward using SSD.

I am now buying on the refurb market Dell R630, single 8 core CPU, 32 GB RAM, iDRAC Enterprise, PERC H330, two 1.9 TB enterprise SAS drives, rack rails, and 5 years NBD support by Dell for $4000.

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