To give better perspective, here is the story....
Presently we are running MOODLE on following H/W configuration.
System Configuration: Sun Microsystems
System Model : Sun Fire 480R
System clock frequency: 150 MHz
Kernel architecture: sun4u
Application architecture: sparc
Hardware provider: Sun_Microsystems
Kernel version: SunOS 5.10 Generic_139555-08
Memory size: 8192 Megabytes
System :SunOS 10v
Harddisk Size :73.40GB*2
OEM# = 0
Origin# = 1
NumCPU = 2
Usage- All the documents are in PDF format. We are running some courses (>150). Registered users >95000.
Problem- During peak hours and half-yearly appraisal cycles the perfromance of server degrades. Users get frustrated. Pages and documens load very slowly. We are planning to use load-balancing with TWO webservers. Pls suggest whichever solution is best has worked for you. In future we might not use Solaris but something like Redhat. Also suggest things to do to improve performance e.g use of higher RAM or use SCSI harddrives etc.