Both versions share the same engine and so offer the same capabilities:

• Up to 12 vCPUs / 64GB vRAM / 2TB vHDDs / 16 vNICs / 8 USB 2.0 ports per VM
• Support for Intel VT-x, VT-d, FlexPriority and EPT
• Support for AMD-V and RVI
• Support for 32/64bit guest OSes (including all flavors of Windows, Red Hat, SUSE, Debian and Ubuntu Linux, FreeBSD)
• Templates and snapshots
• VM full and incremental backups (Windows and Linux guests only)
• VM live migration
• CPU resource limits, prioritization and disk I/O priority
• Cold V2V migration between Parallels Servers Bare Metal hosts (VM to VM, or even VM-to-container / container-to-VM) and hot V2V migration (only for containers)
• Cold P2V migration from physical servers to virtual machines or containers
• Local management console and a CLI for most tasks within a single host
• Parallels Virtual Automation (formerly Parallels Infrastructure Manager) for enterprise management

Today Parallels may be the only company providing a viable virtualization platform for server and client consolidation on Xserve hardware. This will be interesting for classic server consolidation, but it will be a breakthrough if you are thinking about the possibilities regarding OS X based VDI environments. I am definitely looking forward to this release!

VCB binaries will be still available and supported on VI 3.x and vSphere 4.0 according to the support policy, but they will not be included in the new platform. Most partners with a strong focus on backup/restore already support VADP. VMware promises that even more vendors will offer VADP-based solutions in time for the next vSphere release.

So choosing a small block size will not give you an advantage anymore, it will only limit you in the future in case you want to grow your VMFS! Yes, that's another difference, you are not limited to extents in vSphere 4, now you able to really grow your VMFS, which makes it even more flexible. Unfortunately the VMFS wizard will still ask you to format your volume with 1MB block size by default. I would recommend to choose the largest available block size here to be as flexible as possible, because changing it later is not possible.

By the way, it is definitely false information that the chosen block size will impact your storage performance, but: Another highly acclaimed feature by VMware is thin provisioning. As you already figured out yourself, you should be pretty careful using it in your production environment, although there are cases in which it will be very useful. In my opinion thin provisioning also makes sense with larger VMFS block sizes, because increasing the VMDK file in tiny 1MB chunks doesn't look like best practice to me.

Remus is an open source project which provides fault tolerance for virtual machines (VMs) running on the Xen hypervisor. The actual release 0.9 works with tip of the xen-unstable repository, supports paravirtualization and hardware VMs in various 32- and 64-bit configurations for Windows and Linux.

Remus provides transparent, comprehensive high availability to ordinary virtual machines running on the Xen virtual machine monitor. It does this by maintaining a completely up-to-date copy of a running VM on a backup server, which automatically activates if the primary server fails. Key features:

• The backup VM is an exact copy of the primary VM. When failure happens, it continues running on the backup host as if failure had never occurred.
• The backup is completely up-to-date. Even active TCP sessions are maintained without interruption.
• Protection is transparent. Existing guests can be protected without modifying them in any way.

I am looking forward to the day Remus will be announced stable and hopefully integrated into XenServer sooner than later!

Rob Bohmann: Virtualization is like a school bus. Instead of each parent driving their kid to school each day in their car with the resulting traffic jams and waste of time and fuel or having to build lots of extra lanes on the roads, we have the kids ride a big bus that can effectively carry a lot of people. We save resources like gas and space on the highways, as well as the parents’ time.

So if you substitute the energy of gas for the energy in electricity, whether derived from coal or nukes or hydro, etc., and the congestion around schools for the space in your data center and the more efficient management and provisioning of servers, I think the analogy works well, especially for people who are not in the technology arena.

Michael Nunn: Imagine you are a parent of four teenage daughters. All your life you have wanted to provide your daughters with their very own “resources,” like their own bedrooms, their own bathrooms, their own computers, their own clothes, etc., but you just could not afford to do it.

What if I could tell you how to give them all everything they wanted and they really believed that they each had their own bedrooms and bathrooms, but in reality you only had to build one bedroom and one bathroom? You would be well within your budget, your daughters would be very happy, and you would not be using space, materials and money to build all those separate rooms.

Mike Laverick: In the past, the server was a like a very expensive hotel. It was the worst kind of hotel. It only had one big room and only one person could stay there. However, all employees, whether they were the CEO or copy-boy, had to stay there if they were away on business.

This is like the guest operating system being installed to a physical server. Half the time the occupant is out doing other things, asleep, or just lying on the bed surfing up and down the channels looking for the type of channels his wife wouldn’t let him have at home. This is like when Linux or Windows is idling and only using 5% - 10% of CPU or memory. It became considered too costly to build such hotels and filling them with one occupant was very wasteful – because they consume heat, water and power – and most of the time the single occupant either wasn’t there or was asleep!

So someone had the idea of a better hotel, one which was divided into a series of different rooms. Each could be different sizes and offer different qualities of service. It didn’t matter what one guest did in one room, as it could not affect others. This hotel had really thick sound insulation so you couldn’t hear the wedding party downstairs or the newlyweds doing newlywed things next door.

On the top floor beyond the bridal suite, were the penthouse suites which were reserved for the high rollers, specifically for Mr. Exchange, Miss, SQL and Mrs. SAP – but in other floors the rooms were barely large enough to swing a small furry animal – this is where Mr. DHCP and Dr. DNS resided. The old hotel was so expensive only people like Howard Hughes could afford a room there – but this new, more efficient, hotel cost the same to build and maintain – and everyone could find a room that was suitable for their needs – from the odd billionaire to the business man on an overnight stay before catching a flight. It also meant we had to build fewer hotels.

The other thing we discovered was when Mr. Exchange or Miss SQL weren’t around or sleeping – as they were consuming less resources – their resources could be divvied out to the residents in the hotel to improve their experience. It would be easier to get that table in the fancy restaurant, and it was quicker to get served in the bar. Finally, the old hotel model died a swift and untimely death when the economy fell off the end of a cliff. It became increasingly regarded as a luxury no company could afford. The Hotel Virtualization model ruled the roost because it offered the most flexible model of accommodating guest operating systems with their wildly different resource demands.

/etc/vmware/esx.conf

Just search for /boot/memSize = "272" and enter your value. After that you will have to deal with GRUB and the init process, because the settings are boot-relevant. ESX server has proprietary aliases for that, the command is esxcfg-boot. You have to run it twice: First time to regenerate the GRUB configuration files, the second time to recreate the initrd file with the new settings. You might want to use this short shell script, that does it all for you:

sed -i 's/memSize = "[0-9][0-9][0-9]"/memSize = "800"/' /etc/vmware/esx.conf
esxcfg-boot -g
esxcfg-boot -b

Because you have to reboot the host to take effect, so you should plan this for your next ESX patch day.

One of the problems in a virtual environment is to deliver USB devices to virtual machines. Standard ESX VMs don't even have virtual USB hardware and they don't need them. The technology you should use instead is "USB over Ethernet (USBoE)". The idea is to install a driver on the client that comes with virtual USB hardware that reconnects to an USB Device Server or Appliance to use its shared devices.

There are a few appliances on the market, but I learned the hard way that most of them are not suitable for professional purposes. Most of them are not made for data centers and do not come with an 19" option, others do not have an automatic reconnect to their devices after a reboot, which is vital for sharing dongles for copy protected server software. These appliances are cheap and available for under $150, but to me the best solution is a server full of USB PCI adapters and an USBoE software package.

I can definitely recommend Fabulatech's "USB over Network" software, which works really fine though it is not the cheapest solution. Check out the trial version, I'm sure you will be satisfied with the results.