Hello there, I'm trying to understand the interaction between the ext4 `commit` interval option, and the `vm.dirty_expire_centisecs` tuneable. The ext4 `commit` documentation says: > Ext4 can be told to sync all its data and metadata every 'nrsec' seconds. The default value is 5 seconds. This means that if you lose your power, you will lose as much as the latest 5 seconds of work (your filesystem will not be damaged though, thanks to the journaling). The `dirty_expire_centisecs` documentation says: > This tunable is used to define when dirty data is old enough to be eligible for writeout by the kernel flusher threads. It is expressed in 100'ths of a second. Data which has been dirty in-memory for longer than this interval will be written out next time a flusher thread wakes up. Superficially these sound like they have a very similar effect. They periodically flush out data that hasn't been explicitly fsync'd by the application. I'd like to understand a bit more the interaction between these. What happens when the ext4 commit interval is shorter than the dirty_expire_centisecs setting? (Does the latter become "redundant"?) What happens when the dirty_expire_centisecs setting is shorter than the ext4 commit interval? Thanks,
