File System Alignment in Virtual Environments

In speaking to my fellow Implementation Engineers and team leads, I’ve come to learn file system misalignment is a known issue in virtual environments and can cause performance issues for virtual machines.  A little research has provided an overview of the storage layers in a virtualized environment, details on the proper alignment of guest file systems, and a description of the performance impact misalignment can have on the virtual infrastructure. NetApp has produced a white paper that speaks to file system alignment in virtual environments: TR 3747, which I’ve reproduced below.

In any server virtualization environment using shared storage, there are different layers of storage involved for the VMs to access storage.  There are different ways shared storage can be presented for the hypervisor and also the different layers of storage involved.

VMware vSphere 4 has four ways of using shared storage for deploying virtual machines:

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