I need to keep the old hardware version to allow compatinility with 3.5 hosts in the cluster,,,, what are the downsides if i upgrade the hosts but not the VM hardware version?
also, can I run th VI3.5 client and the VSphere 4.0 client on the same machine?
If you don't upgrade the hardware you just can't take advantage of newer hardware version 7 features. You can potentially loose NIC settings if you upgrade tools before the hardware version. You can have both versions of the VI client on a PC. When you start the vSphere client and connect to ESXi 3.5 it'll switch you to the 2.5 client.
I need to keep the old hardware version to allow compatinility with 3.5 hosts in the cluster,,,, what are the downsides if i upgrade the hosts but not the VM hardware version?
No FT, no hot-add, not new drivers, ...
But you can run with any problem.
Also you can upgrade VMware Tools without problems.
also, can I run th VI3.5 client and the VSphere 4.0 client on the same machine?
As written before, yes
Andre
Should all be no problem.
And if you are using VUM, just create baseline to upgrade tools and hardware, with this everything went "alomost" automatically!
MCP, VCP