The ZFS Raid is not an overkill, especially when You do use to protect your data in a raid. So when one virtual disk is corrupted, the ZFS raid can restore that virtual disk. That's why I do use it. I don't trust a single virtual disk, if it gets corrupted, I co loose a lot of data, netiher iI do want to take all the time snapshots or backups of the virtual machine. So the me, ZFS Raid is necessary in the guest, and to me, it would be perfect if it was included in ESXi on the host side. Because this way, I can protect the host as well. ZFS is great in this regard You can take snapshots of Your filesystem, and to backup, clone your filesystem in a quick, efficient way. So it would be a great filesystem to run on the host side too. The snapshots of VMware could even be replaced as well, with the use of ZFS, this way, the footprint of ESXi would be even smaller as well. As ZFS does provide NFS functionality, which could be use to have shared folders, without to have a large foorprint. Another major issue, because even Microsoft is paying an University to have a NFS v3 driver for their OS.
I do known the VMware products from day they were born. Actually I am amazed they did develop from a small company to a nice, big company. Maybe I should talk again with them to push them to a new frontier... I just need to find the one who I did talk too. But those guys are open to critics, comments and aprovements. I do belief in the product of VMware. If You can hold te market for several years, it does mean something. Of course some things need to be improved, but I am sure they will manage. And don't forget, with their products, they did a MAJOR push forward to have more efficient computers, servers and they did help to have a better, nice and green environment. Well, in this regard, I do support them.
The product was one of the first hypervisors, and they did major evolution in different directions. As I did suggested a lot in those days too. One of those things did form the base of VMware server etc. I did suggest that in times, when the site did look like pretty Russian with a lot of servers on the frontpage. I did have some good debates with the developers, to transform VMware workstation to bare metal. A pity, it looks like they did choose some linux os, it would be much better to start from the BSD kernel, which is still, much stronger as the linux kernels in many aspects, where the network stack if very good as well. In this regard, there could be a native port for the BSD community too. Now we need to stick with a linux version, which does not run as smooth as a native version on FreeBSD. To me one of the best server OS is FreeBSD. Reason why there are such great products such as pfsense, FreeNAS, maybe soon a native hypervisor, named BHyVe.
I did try Xenserver, but I was disappointed about the limitations. More, I see, the VMware product van manage perfectly FreeBSD ZFS with 64 LBA in the host. Xenserver as Virtualbox can not manage that at all for some reason. VMware does ! My FreeBSD 64 bit is running with GPT formatted ZFS raid. Other hypervisors do deliver me an int13_harddisk: function 42. Can't use 64bits lba As there are to much limitations on the free version of Xenserver.
Besides, Xenserver is a Citrix product, they are standing too close to Microsoft. Reason why remote desktop products and hypervisors of Microsoft were actually at start, degraded versions of CItrix products.
No, I do use VMware for developement. And I do want to run ESXI, because in this way, I can swap very easy, virtual machines from ESXi to VMware Workstation, so I can run the virtualized, development server on my laptop when I am in hotel, and move it quickly to the server when I am back from projects at home.
But I have a lot of questions related to the hardware comptability. the ESXi should run on every server, every computer. Without any excuse. They can provide warnings, that some drivers do slow down the hypervisor, but a low cost server, workstation should run ESXi. So I am looking forward to the ESxi 5, where there is the possibility to make your custom hypervisor, so You can load all drivers, which should be needed to run on a lowend computer.