Why wait, if the disk is idle?

Posted Sep 9, 2009 22:30 UTC (Wed) by Richard_J_Neill (subscriber, #23093)
Parent article: ext4 and data loss

I understand why the optimisations are a good idea on very heavily loaded system. Likewise on a laptop-mode machine which spins down the HDD.

But in all other cases, if the disk is idle, surely the OS should flush as soon as it possibly can? What benefit occurs from waiting 30 seconds (to have more efficient writes) if the disk isn't running flat-out at this instant?

Why wait, if the disk is idle?

Posted Sep 11, 2009 15:48 UTC (Fri) by nix (subscriber, #2304) [Link]

Even some non-laptop systems (e.g. WD GreenPower drives) can spin
themselves down a bit to save power.