While updating packages on our CentOS server I got the following message:
Downloading packages: Delta RPMs disabled because /usr/bin/applydeltarpm not installed.
Do I need to do something about that? Should I just ignore this?
You don't need to do something, but you can, especially if you have a slow internet connection. If you install deltarpm support:
yum install deltarpm
you will download only the differences with older versions of already installed packages. This is done at the cost of increased processing time.