Esrally command line parameters

Hello,
I am running a set of rally tests and I would like to preserve data/index and run next time with existing data in elastic.

I tried to use --preserve-install=true option but it is not accepted.
esrally: error: argument --preserve-install: ignored explicit argument 'true'

running just --preserve-install remove the entire index.
esrally --pipeline=benchmark-only --track=eventdata --track-repository=eventdata --challenge=bulk-update --track-params=bulk_size:10000,bulk_indexing_clients:32 --target-hosts=localhost:9200 --client-options="timeout:240" --preserve-install

what is the way to pass the parameters to the esrally to preserve the index?

Also, running Rally this way:
nohup esrally --pipeline=benchmark-only --track=eventdata --track-repository=eventdata --challenge=bulk-update --track-params=bulk_size:10000,bulk_indexing_clients:32 --target-hosts=localhost:9200 --client-options="timeout:240" --kill-running-processes > /dev/null 2>&1&

What is the way to track rally progress? running rally without background it prints the progress information to the console but how to track the optput in case of nohup?

Thanks

You need to skip the operation that deletes the index.
To find the name of that operation, apart from looking at the challenge itself, you should familiarize yourself with the info subcommand.

Then you can use e.g. esrally info --track-repository=eventdata --track=eventdata --challenge=bulk-update

Once you've identified the name of the operation that deletes the index, you can specify that together with exclude-tasks.

You are redirecting the output to >/dev/null so you are losing the contents, which otherwise, had you redirected to a file you might be able to reference (even though, the interactive progress would look messed in a text file).

Why do you run with nohup? Can't you run esrally within a screen or tmux session to ensure it stays running even after you disconnect and re-attach the session later?