Hi there,
I am currently evaluating all popular hypervisors and ESXi is the last one I am trying. I have an issue which I am really hoping someone can point me in the right direction because it's frustrating and vmware appears perfect other than this one issue.
How the environment is set up
2 physical hosts, each with the following: 28 cores, 56 threads, 256GB RAM, 4 * 10GBe NIC, 2 * 1GB NIC, 4 * enterprise SSD drives
two of the 10GBe are in a 10GBe switch connected to the SAN (MD3800i + MD1200i expansion with 15k drives)
two of the 10GBe are in a 10GBe switch for the Virtual Machine Network
two of the 1GBe are used for the management network (with redundancy)
Configuration
So although I'm new to VMWare, I have managed to configure the hosts in a cluster with HA, connect to the iSCSI SAN, pretty much everything I need and all works fine.
Performance
So here comes the issue. In other hypervisors I am getting around 400MB/sec between two VM's (it's all 10GBe so you'd kind of expect around 800+MB, thus why I am trying VMWare to get the expected speeds). With VMWare, if I try and copy to another VM or even copy a large file on its VM local C drive, I am getting around 40-120MB/sec.
Observations
I have noticed that if I copy the file once (which happens very slowly), the next time I copy it, it runs at the expected 800-850MB/sec to another VM or 1.2GB/sec local. I presume this is because it has somehow cached the data.
Things I've tried
So I've tried moving the cache to the local host (SSD's) although I know this isn't ideal for HA, I've tried storing it with the VM in the SAN, I've tried giving the VM a huge pagefile (30GB+) and even removing it completely. I have tried passthrough iSCSI drivers, Logic SAS drivers, everything I can think of.
I am hoping it will be something really silly because there's no reason for this awful performance and I don't get this with any other hypervisor so I'm hoping it's just a setting that I've missed somewhere.
Thanks in advance for any help with this - I have 40 days left of the trial so hopefully I can get to the bottom of this before then.
