We are setting up an ESXi 4.1 server that will host 2 vm's for now, maybe 1 or 2 smaller vm's later. The server is a Dell Poweredge T610 with 2 six-core 2.66ghz Xeon processors, 16Gb ram, local storage (4 x 300Gb in Raid 5). One VM will be running an Oracle DB on Windows Server 2008 R2 64 bits, the other will be running also an Oracle DB on Windows Server 2003 R2 32 bits, each serving about 20 users.
How many vcpu's and ram would you recommend to assign to each vm for this kind of usage ? Even though we have 12 vcpu we can assign, I've read that assigning too many vcpu to a VM might cause a drop in performance (cpu contention ?).
We thought of using 6 vcpu / 8 Gb ram for the 2008 R2 server, and 4 vcpu / 4 Gb ram for the 2003 R2 server.