Part 1 Whoa, that's a loaded question and one that will normally bring you down a "rat hole", depending on who you ask. I have attempted to answer this question in the past but things have changed a bit since then (I think it was early last year, check my previous answers). Let's take a fresh look at storage virtualization. There are a few ways to virtualize storage access: In-Band appliance
Hardware based (either HBA based, switch based or storage based) I think the best way to approach storage virtualization is to wait for a standard to arise from the Storage Network Industry Association. The desired goal in my perspective is to get to the point where all vendors agree on a standard way to do it. The end point is to have a single API for interconnection into a SAN file system. This would mean that no matter which operating system you use or which hardware platform, data that is encapsulated into a SAN environment, no matter whether it is accessed via FCP, IP, VI, iSCSI, etc., you will be able to share data between all environments. That's asking a lot. It would require participation of all the HBA, switch, storage and operating system vendors. Some vendors are pushing ahead on their own and creating their own techniques to get to virtualized storage. My thinking is that someone will come up with a better widget and everyone else will adopt that widget as the best practice for storage virtualization. In other words, the market will decide based on industry acceptance and magnitude of deployment. IBM, Brocade, Veritas, EMC, HDS, DataCore, McData, Falconstore, HP, JNI, Emulex, QLogic, Microsoft, Sun, Oracle, Cisco, etc. and others are all doing some sort of virtualization today using different methods. Sun has a storage file system
Brocade is doing it in the fabric
Cisco is doing it in the fabric
DataCore is doing it in the fabric and in-band with appliances and software
HP is doing both hardware and software
IBM is pushing the storage tank
Veritas is using software
EMC is doing it in hardware and software
HDS is doing it in hardware and software
Falconstor is using the appliance method
Microsoft wants to own it and is working on APIs and a file system
Oracle wants to use the database as the file system
Compaq was pushing Versatore which used smart out-of-band appliances AND smart HBAs to virtualize data paths The list goes on and on and I'm SURE I have left out many other players, some of whom I have yet to hear about. So what can you do today with all the choices available and all the different methods to achieve the same goal? It depends on your application and your budget. The in-band approach currently works well. You simply place an appliance running virtualization software in the data path, hook up anyone's storage on the back end and off you go. Click here for Part 2.
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