We have an older cluster using 2 Dell 6850's with 64 gigs of RAM.
We are going to be upgrading the cluster to use 2 Dell R900's with 128 gigs of RAM.
However, the plan to upgrade is going to involve having all 4 nodes in the cluster at the same time.
What I can not find is any documentation about running a cluster with dissimilar hardware. Is this even supported? My guess is that it's definitely not a best practice, but my greater concern is if it's even a supported configurtion.