Throttle The Disk I/O Rate: Limit disk I/O For rsync Tool on Linux and Unix

I run a backup script called /root/backup.sh which runs rsync command. However, rsync makes a lot of disks 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 drive. 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 using rsync command

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/
OR
# rsync -av --delete --numeric-ids --relative --delete-excluded \
--bwlimit=10000 \
/var/www/html vivek@server1.cyberciti.biz:/backups

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:

• How To Avoid Sudden Outburst Of Backup Shell Script / Program Disk I/O

Category	List of Unix and Linux commands
File Management	cat
Firewall	Alpine Awall • CentOS 8 • OpenSUSE • RHEL 8 • Ubuntu 16.04 • Ubuntu 18.04 • Ubuntu 20.04
Network Utilities	dig • host • ip • nmap
OpenVPN	CentOS 7 • CentOS 8 • Debian 10 • Debian 8/9 • Ubuntu 18.04 • Ubuntu 20.04
Package Manager	apk • apt
Processes Management	bg • chroot • cron • disown • fg • jobs • killall • kill • pidof • pstree • pwdx • time
Searching	grep • whereis • which
User Information	groups • id • lastcomm • last • lid/libuser-lid • logname • members • users • whoami • who • w
WireGuard VPN	Alpine • CentOS 8 • Debian 10 • Firewall • Ubuntu 20.04