Actually, idle priority is not allowed for non-root processes. So your sudo... line works, but tracker (running as non-root) cannot ionice itself to idle. There's some good explaination on the web why idle is only allowed for root (IIRC an idle I/O-process could starve a depending realtime process to death or something like that).
For now, I for my part have uninstalled tracker, as it reindexed my whole $HOME (with both some big and many small files) again and again. But i'll stay tuned and retry it when the next minor release hits the repositories.
Actually, idle priority is not allowed for non-root processes. So your sudo... line works, but tracker (running as non-root) cannot ionice itself to idle. There's some good explaination on the web why idle is only allowed for root (IIRC an idle I/O-process could starve a depending realtime process to death or something like that).
For now, I for my part have uninstalled tracker, as it reindexed my whole $HOME (with both some big and many small files) again and again. But i'll stay tuned and retry it when the next minor release hits the repositories.
Ciao
Martin