I'm adding this answer because this topic shows up as a top hit for a similar problem. When we were doing an install using Centos instead of RedHat, we had a similar problem starting. However, instead of missing a library, the error was something along the lines of
/root/arcgis/server//framework/runtime/xvfb/Ubuntu/Xvfb: No such file or directory
The error comes as a result of the init_xvfb.sh
script trying to figure out what Linux distro it is running on. Just comment out lines 74 and 75 in the script as shown below. This will cause it to run the RHEL binary, and everything appears to work from there.
# try to use the system one if it's there
if [ -f /usr/bin/Xvfb ]; then
XVFBBIN=/usr/bin/Xvfb
elif [ -f /usr/X11R6/bin/Xvfb ]; then
XVFBBIN=/usr/X11R6/bin/Xvfb
else
# fall back to our own
if [ -f /etc/SuSE-release ]; then
XVFBBIN="${XVFBHOME}/SuSE/Xvfb"
#elif [ -f /etc/lsb-release ]; then
# XVFBBIN="${XVFBHOME}/Ubuntu/Xvfb"
else
XVFBBIN="${XVFBHOME}/RHEL/Xvfb"
fi
fi