Where to start and where to end?
Some that I can think of:
- Unsupported hardware --> check HCL at http://www.vmware.com/resources/compatibility/search.php
- Compatibility issues --> http://www.vmware.com/pdf/vsphere4/r40/vsp_compatibility_matrix.pdf
- Storage issues --> choose the correct storage for your needs: shared storage vs. local storage, LUN/disk sizes, controllers, write cache
- hosts over or under utilized --> make an assessment of what you want to virtualize (CPU, IOPS, RAM, disk space, ...)
- Overcomitment of CPUs (e.g. 4-8 vCPUs for a VM) --> use less vCPUs
- Snapshot issues --> http://kb.vmware.com/kb/1015180
- Networking setup --> http://www.vmware.com/files/pdf/virtual_networking_concepts.pdf
- VMware Tools --> always install VMware tools in the VMs
- Backup --> Snapshots are no backups! Make sure you have a backup strategy.
- Keep yourself up to date --> e.g. VMware KBs at http://blogs.vmware.com/kbdigest/
Have a look at the VMware Support Microsite - they keep an updated list of the 10 most popular KB articles:
This isn't necessarily a 10 top issue list but last year Petri did a 10 top steps for improving VM performance.
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