VM dropping packets when powering on other VM's

Hello,

I have 2 vmware hosts, both connect to an iSCSI SAN, and all VM's are on same lun.


on Host A
I have SBS 2011 running
and Server 2008 R2 running

Both VM's share the same physical nic and Vswitch for general network access

On Host B
I've got various vm's running of various OS's
All VM's share same physical nic and vswitch for general network access


Again, all vm's , for both hosts, are stored on same ISCSI SAN


If I power on ANY VM on host B, the SBS 2011 server on Host A instantly starts lagging. Well before any guest OS loads.

Pings to the SBS Server are extremely high in terms of latency, and some will drop as well.

However, pings to the Server 2008 guest on Host A are fine, and never drop or become latent....

Drivers from both vNIC's on both guest vm's of host A are identical

i'm wracking my brain over this one....whoever can figure this one out deserves 1,000,000,000 points
LVL 3
Tom-J-LaelAsked:
Who is Participating?
 
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
It seems like your datastore is struggling with performance issues.

Is all the equipment on the Hardware Compatibility List?

Are all firmwares up to date?

Do you have a storage network just for iSCSI?

Do you have Jumbo Frames enabled?

Have you created your iSCSI network as per Best Practice?

What is the SAN spec?

Is this a new installation, and you've always had this issue, or has this just started to occur with more loading

see my EE Article, Step by Step Tutorial Instructions with Screenshots

HOW TO: Enable Jumbo Frames on a VMware vSphere Hypervisor (ESXi 5.0) host server using the VMware vSphere Client

HOW TO: Add an iSCSI Software Adaptor and Create an iSCSI Multipath Network in VMware vSphere Hypervisor ESXi 5.0
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coolsport00Commented:
Agree with @hanccocka here. If you go into the Shell of the Host this VM is on, type "esxtop" (without the quotes), then "v" to get to the right resource view. What does the DAVG metric show during this process? If above 10-12, you have disk latency. If this is the case, what is your Datastore configured with (RAID, disk type, etc.)?

Regards,
~coolsport00
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Tom-J-LaelAuthor Commented:
I have the right mind to believe that the issue was due to the switches dedicated for the iscsi.

We used Dell's try and buy program to put some PowerConnect switches in place and overall performance improved, however, the performance increase was not to the extent that the client wanted to pay the price for the switches.
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