On Wednesday November 9, carlos@xxxxxxxxxxxxxx wrote: > Neil Brown (neilb@xxxxxxx) wrote on 10 November 2005 09:50: > >> Is intent-logging for raid5 already in mainline or only in -mm? I > >> looked for it in 2.6.14 and found nothing... > > > >raid5 is in 2.6.14. raid6 and raid10 should be in 2.6.16. > >What did you look for? > > Some doc, or compilation option. I suppose it's always on then and > just using --re-add with mdadm is enough. No, you have to tell an md array to use an intent bitmap. If you can do this to a running array with e.g. mdadm --grow --bitmap=internal /dev/md1 > > >I'm not sure what you mean by 'went out of sync'. > > I wasn't clear, I meant a device failed. > > >When an array is active and being written to, many stripes could be > >out-of-sync at any time, as writes have been started, but haven't > >completed yet. Intent logging record the intent to write somewhere > >before doing the write, and then clears the intent sometime after > >the write completes. > > > >After a crash, some intents will still be recorded, and only the > >stripes associated with these risk being out-of-sync, so only those > >need to be resynced. > > What about the writes that were started and completed after the > failure? If the array is degraded, intents are not removed from the bitmap, so these writes will still be recorded in the bitmap. NeilBrown - 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
