I run a backup script called /root/backup.sh which runs rsync command. However, rsync makes a lots of disk I/O and network I/O. I would like to reduce both disk and network I/O. My server has 10Mbps server connection with 160GB SATA hard disk. How do I reduce disk I/O so that the entire system does not die or become unresponsive?
This is a well known issue. There are two methods to control or throttle the disk and network I/O rate under UNIX / Linux while using the rsync command.
Method # 1: Limit I/O bandwidth
The –bwlimit option limit I/O bandwidth. You need to set bandwidth using KBytes per second. For example, limit I/O banwidth to 10000KB/s (9.7MB/s), enter:
# rsync --delete --numeric-ids --relative --delete-excluded --bwlimit=10000 /path/to/source /path/to/dest/
Method # 2: Take control of I/O bandwidth using ionice utility
The ionice command sets the io scheduling class and priority for a program or script. You can totally control disk i/o. See the following article for detailed examples: