Followup to: <200407302338.33823.maarten@xxxxxxxxxxxx> By author: maarten van den Berg <maarten@xxxxxxxxxxxx> In newsgroup: linux.dev.raid > > On Friday 30 July 2004 23:11, maarten van den Berg wrote: > > On Saturday 24 July 2004 01:32, H. Peter Anvin wrote: > > > I'm still early in the testing phase, so nothing to report as yet. > > But I have a question: I tried to reproduce a reported issue when creating > > a degraded raid6 array. But when I created a raid6 array with one disk > > missing, /proc/mdstat reported no resync going on. Am I not correct in > > assuming that raid6 with 1 missing drive should at least start resyncing > > the other drive(s) ? It would only be really degraded with two missing > > drives... > > > > So instead, I defined a full raid6 array which it is now resyncing... > > My resync speed is rather slow (6000K/sec). I'll have to compare it to > > resyncing a raid5 array though before concluding anything from that. Cause > > this system is somewhat CPU challenged indeed: a lowly celeron 500. > > To confirm, after stopping the raid6 array (didn't want to wait this long) I > created a raid5 array on the same machine and it resyncs at 14000K/sec. > Is this expected behaviour, the 6M/sec for raid6 vs 14M/sec for raid5 ? > I suppose raid6 has to sync two drives, which would maybe explain the speed > difference(?) In any case, hdparm -tT report 50M/sec on each single drive. > Is this discrepancy in speed normal ? > (yes yes, I played with the /proc/sys/dev/raid/ speed settings (to no avail)) > A newly created RAID-5 array uses a special trick to do the initial sync faster. Unfortunately that trick is not possible for RAID-6. -hpa - 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
