Virtualization - What Now?

Dogcatcher said:

On the Asus and Intel boards, are you using Core 2 Duo or Core 2 Quad? If you have a mix, do you see any substantial performance difference running ESXi on four rather than two cores?

My Intel board runs an Core 2 Quad (Q9400) and my Asus boards run a Core 2 Duo (E8400). For what I do with the boxes, I don't really see much difference at all.

Dogcatcher said:

What amount of RAM are you putting in these virtual server boxes?

I have 8GB of RAM in each of these boxes...as it's the max that my boards will take. This easily allows me to run 5-10 concurrent boxes. With ESXi, it does a fair amount of memory sharing, ballooning and swapping techniques...hence you can "over-allocate" RAM and things will continue to churn away like normal as VMWare will shift the RAM around as the VM's need it.

In my production ESXi servers, I usually run 20-32GB of RAM in each box.

Dogcatcher said:

In addition to your use of ESXi, have you used the Xen hypervisor? If so, how would you compare them?

No, I haven't used it. The shops that I have been in have been VMWare users...and it's worked very well for me, so I haven't played around at all with Xen.

Well, one's a microkernel and one's a macrokernel (Xen/Hyper-V are microkernels, VMWare uses a macrokernel), which affects performance. For instance, CPU performance and RAM performance are generally much better in a microkernel architecture, but disk I/O throughput is usually much better in a macrokernel design. A macrokernel provides all hardware drivers for the hardware in the OS running in the root partition on the hypervisor which increases performance (versus a microkernel which uses the drivers passing through the root partition), but this can be a drawback too - a misbehaving driver in a specific VM can take down the whole parent VM server in a macrokernel hypervisor OS, versus a VM problem on a microkernel system being less impactful on the parent OS and hypervisor, meaning less impact on other VMs on that hypervisor.

There are all kinds of differences, and no one design is "better" than the other except in very specific scenarios, so it depends more on the OSes you're planning on virtualizing and the price you are willing to pay (and of course whether or not you've already decided on a different solution already). Windows shops, or shops that run specific non-Microsoft OSes probably should consider Xen or Hyper-V, because there's more flexibility in hardware choices (another microkernel benefit over macrokernel) and thus driver availability is much greater, but shops that are running many different OSes probably want to look at a macrokernel design like VMWare because there's more flexibility in the VM hosts that can run natively (the converse of having more choice in underlying hypervisor server type/OS).

cowpatty said:

1) how well does EXSi deal with both Linux files as well as Windows files?

Perfectly fine as these are all individual virtual machines...so the virtual linux machine is just that and so is the virtual linux box.

cowpatty said:

My concern here is that I am struggling with "if" i can raid my boot drives, which I suppose most be Linux compatible, while the disk drives that work with Windows 7 apps must be NTSF?

Raid the boot drives of what???? The virtual machines themselves...or the ESXi hypervisor machine? It doesn't necessarily make sense to RAID the boot drives of any of the VM's as they are going to only run as fast as the disks in the hypervisor itself.

As far as RAIDing the hypervisor, the boot drives don't do much. It's a very, very small OS. In fact, it boots in about 15 seconds and weights in around 180MB of disk space.

The drives comprising your datastores (where your VM's live), now that is a different story altogether. These can be raided and most likely will need to be raided for best performance...but they have to come from a server class RAID board or a few consumer class boards like the Adaptec 2405 PCI Express RAID card (which can do RAID 0/1/10). In other words, pretty much no onboard motherboard RAID is going to work in an ESXi box.

The other option is to use a dedicated storage box and connect the ESXi hypervisor to it via Fibre Channel (expensive), or iSCSI (pretty much free). You could use something like FreeNAS or OpenFiler (both free) on a commodity box and RAID your drives there...and then access them over iSCSI Nic's across the network. Of course, your speed is then limited by the NIC's themselves rather than the spindle speeds of the drives.

The underlying drives under ESXi are formatted as VMFS (vmware file system). However, the virtual machines format their VMDK files (their own virtual hard drives) and use whatever file system type the virtual OS supports. So, linux might be EXT2/3/4, while Windows would be FAT32 or NTFS.

cowpatty said:

2) From what i can read (not clear), a new system build on EXSi, may require multiple boxes, one for the EXSi console and a second box to do the work.

This is correct. The ESXi box is a linux based console...Thus, no GUI. You cannot manage the VM's from the console of the ESXi box. Instead, you must install the VMWare vSphere client (free) on a Windows/Linux host with a GUI and connect remotely to your ESXi box to manage it.

Hope this helps.