Will VMware vSphere 5.5 work on a Dell Poweredge R300?

We just got a bunch of new Dell servers with current vSphere & vCenter versions (5.5, with possible future upgrade to 5.5U1). We'd like to add our older Dell R300 servers (Xeon 33xx series and onboard SAS6/iR controller, currently running ESXi 5.1 and still under support contract) to the same vCenter but Dell and VMware say they only support up to vSphere 5.1U2.

Now we need to choose between trying to run everything on 5.5 (if it runs on the R300s) or downgrade newer gear to 5.1 (we can still do that since the newer machines are not yet in production) or run a vCenter 5.5 with some 5.5 nodes and some 5.1 nodes until we refresh the older hardware (will probably be in the 12~18 months range).

Is vSphere 5.5 actually incompatibile with R300s (i.e., won't run) or is it just not covered by "official support" because they're older servers but runs anyway?

Your Dell PowerEdge R300 servers will likely work with ESXi 5.5.

VMware host compatibility is usually a function of three things:

• System chipset - Including processor requirements, CPU virtualization extensions, etc.
• Storage controller - In order to see local disks and/or hardware RAID controller support.
• Network adapters - Because: networking.

However, it's possible to use "unsupported" hardware in VMware as long as you're aware of the drivers and components that comprise the server build. You can always substitute known-good network adapters and RAID controllers. This is common in the "Whitebox" world, but more effort than necessary for a professional.

For systems that were previously on the HCL, this is just gentle hint to move on and plan to decommission your older gear. An HP ProLiant DL370 G6 server that worked well with ESXi 5.1 won't just stop working (or catch fire) under 5.5 just because it's dropped to the unsupported list.

From the vendor's standpoint, it makes sense to limit the number of "supported" systems that need to be tested and validated with each software revision/release. I think the support lifecycle is 4-5 years. Generous enough.

From the customer's standpoint, you should evaluate whether it makes sense to use such old and lmited equipment in a modern vSphere environment. If this is a clustering situation, do you really want to mix 2008-era CPUs and resources with newer servers? You can play VMware EVC games, but it's still not ideal. And that's coming from a RAM capacity, power consumption, CPU features and performance perspective.

If these are standalone hosts, they're right on the edge of being useful as hypervisor systems. A lot has changed in six years.