ESXi 5 - using VMFS Datastores >2TB?

[Gr-R]

We can define VMFS5 Datastores larger than 2TB on ESXi 5.

I have some questions?

1. If we increase LV on DSS from 2TB to 4TB, is it possible to "increase&convert" 2TB (VMFS3) Datastore (originally created on ESXi 4.1) to 4TB (VMFS5) Datastore, yet or ever?

You can grow the volume from the DSS V6 webGUI, the conversion needs to be done on the vmware side. I suspect you need to make the conversion before growing the volume.

2. I see, using one big LUN is much more flexible than 2 smaller, but if we compare the speed, is there any difference? By myself, I've noticed very low benchmark using GPT on Win64 systems. I know, this is very different OS, but...

This really shouldn't affect speeds(provided it doesnt cross arrays), it's more of a management issue.