Workload Distribution and VMFS LUN Sizing relations
Posted by techstarts on September 24, 2007
Because virtual machines share a common VMFS, it might be difficult to characterize peak‐access periods or optimize performance. You need to plan virtual machine storage access for peak periods, but different applications might have different peak‐access periods. The more virtual machines are sharing a VMFS, the greater the potential for performance degradation due to I/O contention.
Therefore VMware recommends that you load balance virtual machines over servers, CPU, and storage. You should run a mix of virtual machines on each given server so that not all experience high demand in the same area at the same time.
However this no definitive size recommended but common LUN size is around 300-700GB.As you can see Workload nature can be influencing factor in deciding the LUN Size. For more information please have a look at page 37, San configuration guide.
When making your LUN decision, keep in mind the following:
- Each LUN should have the right RAID level and storage characteristic for applications in virtual machines that use it.
- One LUN must contain only one single VMFS volume.
- If multiple virtual machines access the same LUN, use disk shares to prioritize virtual machines.
