Neil Brown ([EMAIL PROTECTED]) 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. >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? >> I thought that another way to speed >> re-sync would be to not sync the blocks that were written to the array >> after it started, since they should be already up to date. Is there a >> way to do this? Does intent-logging takes this into account? > >intent-logging does not try to take this into account. The chuck-size >for intent logging is usually quite large. A single write it >unlikely to completely update an intent-chuck, so would need to keep >track of lots of recent writes to see if any collection of them >completely cover any intent-chuck. The effort isn't worth it for the >saving. It'd be useful for starting an array and filling part of it with data because the sync wouldn't have to be done for the written part. When you deal with 500+GB arrays used more than 50% it'd be significantly faster. I understand that it's quite a specific situation though. - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
