On Wed, 11 May 2011 09:39:27 +1000 Steven Haigh <netwiz@xxxxxxxxx> wrote: > On 11/05/2011 9:31 AM, NeilBrown wrote: > > When it finished you will have a perfectly functional RAID6 array with full > > redundancy. It might perform slightly differently to a standard layout - > > I've never performed any measurements to see how differently. > > > > If you want to (after the recovery completes) you could convert to a regular > > RAID6 with > > mdadm -G /dev/md0 --layout=normalise --backup=/some/file/on/a/different/device > > > > but you probably don't have to. > > > > This makes me wonder. How can one tell if the layout is 'normal' or with > Q blocks on a single device? > > I recently changed my array from RAID5->6. Mine created a backup file > and took just under 40 hours for 4 x 1Tb devices. I assume that this > means that data was reorganised to the standard RAID6 style? The > conversion was done at about 4-6Mb/sec. Probably. What is the 'layout' reported by "mdadm -D"? If it ends -6, then it is a RAID5 layout with the Q block all on the last disk. If not, then it is already normalised. > > Is there any effect on doing a --layout=normalise if the above happened? > Probably not. 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
