copying large directory with cp fills memory

Question

We are using rsnapshot for backups. It uses hard links to efficiently store unchanged files, and rsyncs the changed files from servers.

The hard linking part calls a command like this

  cp -al /current /old

But this process uses up ALL the available memory. Is there a way to limit memory of cp process, or is there a memnice utility a la nice/ionice?

Answer 1

rsnapshot includes support for --link-dest support using rsync which would avoid the cp -al step. Rsync 3.0+ doesn't have to keep the entire directory tree in memory and would probably work better in your situation.