One of the things that irks me about vSphere environments is that because things update so quickly, some of the components can be left out of sync. This includes VMware Tools, virtual machine hardware, virtual machine file system (VMFS) versions (even with the VMFS-3 series), host versions, hardware firmware versions, and storage controller revisions to enable features like vStorage APIs for Array Integration (VAAI).
When a host is updated to ESXi 5, existing VMFS-3 datastores can stay as they are or they can be upgraded to VMFS-5. It is recommended to perform new formats on VMFS-5 volumes (see my earlier post on VMFS-5). For the smallest ESXi installations, that may not be an option. Specifically, for the smallest ESXi installations that only leverage direct attached storage (DAS) on local array controllers,new volumes and clean formatting may not be an option.
The process to upgrade a VMFS-3 volume to VMFS-5 is very straightforward. Should the VFMS-3 volume be a SAN volume and shared to many hosts, it is critical that the other hosts are updated to ESXi 5, as it is not readable by ESXi 4.x hosts or earlier. VMFS-3 was pretty slick in that it is forward and backward compatible, but VMFS-5 requires ESXi 5 or higher.
Within the host configuration of the vSphere Client, browse to the storage configuration section. There, the Upgrade To VMFS-5 link is available for the datastore. This is shown in Figure A:
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The other critical consideration with a VMFS-3 to VMFS-5 volume migration is whether or not the virtual machines on the volume can be running. With ESXi 5, they can be running during the upgrade! Pretty slick! There are a couple of pointers to consider, however, before embarking on the upgrade. First of all, make sure that you have backups of the virtual machines. Secondly, if you can have the virtual machines powered off; go ahead and do that. At that point, the upgrade task will begin on the VMFS volume. A quick task is shown in the vSphere Client in Figure B:
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That is it! Further, the virtual machines can stay running on the volume. How easy is that? Do you plan to upgrade VMFS-3 volumes in place on local attached storage? Share your upgrade stories below.