If you are unsure how may MB/sec the array can perform, vxbench is the test tool you are looking for. If you have the number, you can divide by the average transfer rate per client and estimate what is best for you.
Small example:
Examples:
vxbench -w write -i iosize=128,iocount=262144 /diskstu4/dsu/testfile1
output:
total: 111.531 sec 300852.32 KB/s cpu: 48.65 sys 0.04 user
vxbench download page