xtrabackup switches for backup

Hi all,
I am trying to make the backups as fast as possible.
Currently I am using the following switches

innobackupex --no-lock --parallel=8 --rsync /backupdir

Using --no-lock as we were seeing lots of flush table read locks.
What can be the highest value for --parallel switch? I would this is based on number of cores but I’ve gone upto like 200 and it still works.

Also what else can I use here to make the backup even faster?

Thanks!

–no-lock option disables FLUSH TABLES WITH READ LOCK. Is all your tables are InnoDB ? Make sure when using --no-lock option you should execute any DDL during backup in progress or any updates on non-innodb tables. Did you checked “backup locks” this block updates to non-transactional tables and DDL statements for all tables.
To accelerate backups you may use compression along streaming. Check details in documentation https://www.percona.com/doc/percona-xtrabackup/2.2/innobackupex/parallel_copy_ibk.html