Posted on May 28th, 2010 in Tips | 1 Comment »
For the past few weeks, my customers keep received an alarm “Host connection failure” email alerts via VMware vCenter but end up it’s a false alarm.
The email alert example as below:
Target: kulsrvprd01.malaysiavm.com
Stateless event alarm
Alarm Definition:
([Event alarm expression: Cannot connect host - incorrect Ccagent] OR [Event alarm expression: Cannot connect host - network error] OR [Event alarm expression: Cannot connect host - time-out] OR [Event alarm expression: Cannot connect host - time-out] OR [Event alarm expression: Host connection lost])
Event details:
Host kulsrvprd01.malaysiavm.com in DC1 is not responding
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If you are currently deploy the nexus 1000V with the vSphere 4 update 1 and plan to run windows 2008 R2, here are some major issue we had faced for the pass 2 weeks. We experienced all the windows 2008 R2 with packets drop right after the vmotion completed. the Windows 2008 R2 virtual machine will not be reachable from external, but you can ping the gateway from the virtual machine console as usual. After our research and troubleshoot, this was due to the multicast function which seems to be conflict with windows 2008 R2 and become 1 of the major bugs in the Nexus 1000 version 1.2. There are some work around which suggest to turn off the igmp snooping, but our scenario, this didn’t work as it needed. If you are running on windows 2003, you will not experience the situation as we experienced here.
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Many of you may had slowly migrated your vcenter to windows 2008 64 bits or R2 recently. As we know, the vCenter server will still require a 32 bit DSN to connect to the 64 bit SQL database even the operating system are currently on 64 bits. You may able to search this on the google easily which suggest you to execute this command odbcad32 from start run to create the 32 bits client, but this may not work actually. I done twice and I hit the same problem as the ODBC console launch are still 64 bits.
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Some interesting finding to share during the last migration I did. I was performed the cold migration for all the virtual machines on the production. Before we migrated over to the new SAN storage, all the current virtual machines are running with thin provisioning enable from vSphere 4. During the storage migration process, you will need to choose either same as source, thin provision or none thin provision. I had chosen same as source option and perform the storage vmotion. After the storage vmotion done, I realized that the virtual machine had no longer with thin provision enable.
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Yesterday I just did a migration of vCenter server from Physical to virtual. I re-install and configured the vCenter on the virtual machine and manually registered all the ESX host to the new vCenter. 1 of the challenges I faced was the DVswitch. I had created the same DVswitch name and port group in the new vCenter. Guess what, during the migration, the virtual machines network disconnected. I tried to dig around whats went wrong, as I found there was case senstive on the dvswitch. The case senstivie applied and happened on the Hypervisor level but from the vCenter perspective, it may not be the case as Windows does not has the issue with case sensitive. I try to create a new DVswitch port group with the correct case sentitive as I did on the hypervisor previously, vCenter detected as duplicate portgroup name.
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