Slow performance on all virtual machines on an ESX host
You notice a slow performance on all virtual machines on an ESX host, too much IOWAIT?
Open a SSH session on your ESX host and run TOP, and check the IOWAIT% value. Is it constantly high?
Maybe your console is paging a lot! Check the Swap used space, higher than 0K then it’s time to increase the memory allocated to your console.
To change the amount of RAM assigned to the service console:
- Log in to VirtualCenter from the Virtual Infrastructure Client with a user that has administrative rights.Note: If you do not have VirtualCenter, log in directly to the ESX Server host as root .
- From the Inventory select the ESX Server host.
- Click the Configuration tab.
- Click Memory.
- Click Properties.
- On the Memory window enter a value between 256MB and 800MB for the service console parameter.Note: For troubleshooting purposes, VMware recommends that you increase the service console RAM to 800MB.
- Click OK.
Reboot your ESX host and check again IOWAIT Swap used values…