I’ve actually had to change the order of VSAN posts just to make this very point – VSAN is NOT a Virtual Storage Appliance. I’ve seen multiple conversations on twitter, and some blog posts, which are completely inaccurate when it comes to this point. VSAN is completely and fully integrated into vSphere. There are no appliances to push down and no additional VIBs to install on ESXi version 5.5 and vCenter 5.5 – VSAN is built into vSphere as kernel modules.
Now, Frank Denneman wrote an excellent article explaining the advantages of kernel modules over appliances here. I’d suggest reading Frank’s articles as he makes some very good observations. In a nutshell, kernel modules provide the shortest path for I/Os, remove the management overheads of having to deal with a separate appliance, and do not consume resources unnecessarily.
So while the VSAN is many things (converged compute and storage, hybrid solution using combination of SSD & HDD, policy driven storage), it most certainly is not a Virtual Storage Appliance (aka VSA).
You can review previous VSAN posts here.
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