During daily operations, I found following tips may be useful.
DNS resolve error in Amazon EC2
I found a Amazon EC2 instance cannot resolve DNS names. It turned out that the
/etc/resolv.conf file is empty. Modify the file to look like below
The configuration may be different. You can copy it from other EC2 instances.
rsyslog uses too much disk space
rsyslog stores messages in INN news format, which takes a lot of space. Usually you don't need to store them.
/etc/rsyslog.d/50-default.conf and comment out following line:
Reduce load of backup scripts with
Sometimes your backup stripts consume too much resources. You can use
ionice to limit CPU and IO resources it can use.
Following command put
backup.sh into lowest priority and run it.
/usr/bin/nice -n 19 /usr/bin/ionice -c2 -n7 /usr/local/bin/backup.sh