This is a follow-up to my previous post on the 5.0U2. At the same time, VMware also released vCenter 5.1.0b. This post will look at the storage items which were addressed in that update, although the issues that are addressed in the storage space are relatively minor compared to the enhancements made in other areas. Note that this update is for vCenter only – there is no ESXi 5.1 update.
This is possibly the most exciting new storage feature in the vSphere 5.1 release. Space Efficient Sparse Virtual Disks (or SE Sparse Disks for short) were designed to alleviate two issues. Let’s describe these issues first of all. Problem Statement #1 – Let’s take a Guest OS running on a linked clone (View desktop if you will), and this Guest OS issues a 4KB write. vmfsSparse disk (which is the format used by traditional linked clones) has a block allocation unit size of 512 bytes. In other words, this Guest OS is backed by 512 byte blocks. Depending on the…