rados bench error after running vstart script- HELP PLEASE

Hello, I am having an error while trying to run rados benchmark after running vstart script I run : ../src/vstart.sh -d -n -l and then when I try to run: bin/rados -p rbd bench 30 write it gives me error saying: error opening pool rbd: (2) No such file or directory Can someone please help me in this. I will be grateful Thanks