High Availability (HA) and DRS in ESX
Posted by craig - on August 22nd, 2008 in Virtualization |
The HA and DRS features become an important and a must for enterprise usage in production. For the latest updated patch release from VMware, you will realize some changes had been made in the way the HA communicated.
there is an incident for myself that the HA keep disconnect and reconnect automatically for every couple of minutes. The work around is you need to make sure the hostname that you configure for your esx server is still with lower case or upper cases. If you do have mix environment with upper case and lower case in the physical cluster for ESX, you will experience this technical issue due to the way of the HA communication had been tie to the DNS name. In linux, case sensitive is always apply
For DRS, is not recommend to configure to aggressive level as during the vmotion, it do generate the overhead and network traffic for vmkernel port for both original host and destination host. 1 of the test I had done previously, I Vmotion 20 VM to another host in 1 time, and I do face the CPU bottleneck which stop the vmotion activity. Advice here is to Vmotion 1 by 1 if you are not in rush as it will generate less overhead for the vmotion activity and of course higher success rate.
The HA in ESX will only take effect when the Host is having hardware failure or Down. If the VM itself is hang, it will not able to force the VM to be restarted. Latest release virtual center come with features to monitor the status of VM and will force it to be restarted if the VM is hang.
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