On 15 Sep 2011, Nigel Cunningham outgrape: > Hi. > > On 15/09/11 13:31, NeilBrown wrote: >> I think the 'md' device *should* be marked 'clean' when it is clean to >> avoid unnecessary resyncs. > > I must be missing something. In raid terminology, what does 'clean' > mean? Googling gives me lots of references to flyspray :) I thought it > meant the filesystems contained therein were cleanly unmounted (which it > isn't in this case). Just 'cleanly shutdown'? It's got nothing to do with filesystems. Just 'all writes that were issued to this array have reached all constituent devices in the array'. (Which one hopes they have if we're about to power down!) Thus, if an array is dirty, one or more writes is presumed to have not got to one or more devices, so a resync is required. (The update of the superblock's state from dirty to clean is done lazily because the state changes very frequently and it means another write, so arrays can be briefly marked dirty if they are in fact clean, but should never be marked clean if they are in fact dirty.) -- NULL && (void) -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
