High CPU wait, I/O and Load Average while backup is generated in Plesk.
/usr/bin/pigz consumes high CPU resource during the backup process as it is involved in the backup compress process.
There are three possible solutions to reduce the server load during backup process, for that the following options can be enabled under Tools & Settings > Backup Manager > Settings:
- Run scheduled backup processes with low priority
- Run all backup processes with low priority
- Do not compress backup files (this way the backup size will be larger, but load average will be less as
pigzprocess that is involved in the backup compress process will be skipped).
Note: these options increase the backup time. Other server tasks will not be affected.
If there is a highly-loaded domain on a server that takes a lot of server resources, re-schedule the time to start a backup to the night when the number of visitors to the site is less.