What the Heck is Virtualization?

So, what the heck is this virtualization thing that everyone is talking about?  Everyone is getting the idea it's important, but a lot of people talking about it don't seem to understand it.  Take for example, this article over at CNN Money entitled: Dell Spends Big Bucks For VMware like Hardware.  What the heck does that mean?

The article describes a recent acquisition by Dell of a company called EqualLogic.  I surfed over to EqualLogic's web site and found this as the description at the top of their web site:

EqualLogic's storage area networks enable fast, flexible storage setup and provisioning while dramatically reducing the time and cost required to manage, maintain and grow a SAN environment – locally or remotely.

Storage Area Networks are "VMware like Hardware?"  Hmmm.  I think the folks at CNN really don't understand any of the details about what they're saying.  But, if you dig a little deeper, there is a connection.  EqualLogic isn't a competitor to VMware, but it might scare their parent EMC.

While EqualLogic describes their technology as a SAN, that usually implies a Storage Network built over Fiber Channel (where each computer has a dedicated Host Bus Adaptor (HBA)).  Each server talks to storage over this proprietary network instead of over Ethernet.  On the other hand, the part of the market called Network Attached Storage (NAS) let's servers access storage over Ethernet.  This is cheaper and more flexible, but some shops still prefer SAN.  EqualLogic calls their technology SAN, but it's really NAS where the storage is accessed over ethernet via the iSCSI protocol.

So, how does this all connected back to Virtualization?  Well, NAS is really the basic building block of Storage Virtualization.  This is in some ways similar to the Hypervisor being a basic part of Server Virtualization.  When you bring together Storage and Server virtualization you start to gain the ability to realign the resources in your data center at lightning speed.  This allows IT departments to move at speeds far greater than they can today.  The next-generation of data centers will be built with NAS and Hypervisor as core components. Think of one of Sun's Constellation supercomputers where each blade has a hypervisor and all the guest operating systems are hosted on Thumper NAS storage.  That starts to look like the data center of the future.

It appears that Dell is trying to buy its way into the Virtualization market, but not as a direct competitor to VMware or Sun's recently announced xVM.  It'll be interesting to see how this works out for them. 

Comments:

This is a bit of a digression, but I can't help myself!

A lot of the things you can do with storage virtualization can get mind bendingly complex.

I have a lab with a little iSCSI target implemented on Ubuntu that provides an iSCSI target to a VMware ESX initiator instance that has a VMFS filesystem which has virtual disks. (whew!) It also provides iSCSI targets directly to a Solaris x86 virtual machine hosted on that same VMware machine. I don't get a lot of help from any of these components keep all this straight, and fret every time I touch it.

One of the things I understand some folks are doing is creating RAID-Z zpools from iSCSI targets from multiple servers, the idea being to increase availability. I suppose you could create a ZFS filesystem like this and then share it via NFS, and imagine someone has done that.

Of course, just because you can do something doesn't make it a good idea, but I'm sure that even the combinations that make sense will become increasingly complex.

Posted by Louis F. Springer on November 07, 2007 at 05:06 AM PST #

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Thoughts on cloud computing, virtualization and data center management from Steve Wilson, Oracle engineering VP.

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