There is a function named alias, that I tried as given below
http://myhost:80/render?target=alias(my.src.metrics.endTime,"my.target.metrics.success_endTime")
But I want to create my.target.metrics.success_endTime persistent in the graphite for my.src.metrics.endTime. so that new values under the my.src... are also available via my.target....
However, you can't configure persistent aliases in graphite's UI (webapp), you may create symbolic link on the filesystem, that will behave like an alias
./graphite/whisper/my$ ll
drwxr-xr-x 6 graphite graphite 4096 Dec 28 2016 src/
./graphite/whisper/my$ ln -s src target
./graphite/whisper/my$ ll
drwxr-xr-x 6 graphite graphite 4096 Dec 28 2016 src/
lrwxrwxrwx 1 root root 4 Dec 28 2016 target -> src/
Path my.target.* will be findable.
Other soltuion is to use different front/dashboard UI like Grafana and make use of variables - http://docs.grafana.org/reference/templating/