Is there any way to get anything below 2.6.30 to recognize this 'fake' raid6 with all Q blocks on the last disk? I reshaped my raid5 to raid6 using this echo into /sys The 2.6.30 and 2.6.30.1 is terribly unstable with xfs+nfs (1-3 kernel oopses a day and complete resync much of the time) (I have sent a bug report to xfs mailing list, it seems to be xfs/nfs) Best regards, Michael Ole Olsen Neil Brown schrieb am Friday, den 26. June 2009: > On Wednesday June 24, billycrook@xxxxxxxxx wrote: > > On Wed, Jun 24, 2009 at 06:20, NeilBrown<neilb@xxxxxxx> wrote: > > > On Wed, June 24, 2009 8:27 pm, Michael Ole Olsen wrote: > > >> Is it possible to reshape my /dev/md0 raid5 into raid6? > > > > > > If you are are using Linux 2.6.30, then you can > > > > > > echo raid6 > /sys/block/md0/md/level > > > > > > and it will instantly be sort-of-raid6. > > > It is exactly like raid6 except that the Q blocks are all one > > > the one drive, and drive that previously didn't exist. > > > If you have a spare, it will start building the Q blocks > > > on that drive and when it finishes you will have true raid6 > > > redundancy, though possibly a little less than raid6 performance, > > > as a real raid6 has the Q block distributed. > > > > > > When mdadm-3.1 is released, you will be able to tell the raid6 > > > to re-stripe with a more traditional layout. This will take quite > > > a while, but you can continue to use the array (though a bit more > > > slowly) will it progresses. > > > Of course you don't need to do that step if you don't want to. > > > > I have a raid5 array on 2.6.18 that I'd like to grow like this. I > > might wait until mdadm-3.1 so I can stripe Q from the git-go. I'd > > like to --stop the array on the 2.6.18 machine, and export the > > individual disks over iscsi to a 2.6.30 machine, and use the newer > > mdadm there to grow the array from raid5 to raid6. Then --stop it on > > the 2.6.30 machine, unexport the disks, and --start the array again on > > the 2.6.18 machine. Disclaimers aside, should that work? My main > > concern is 2.6.18's ability to work with this 'creative' raid6 > > implementation that currently results from the grow from raid5 to > > raid6. > > 2.6.18 will not understand the raid6 created by simply echoing 'raid6' > in to the 'level' file. It will need to be restriped with the help of > mdadm-3.1 first. > > > > > I've also got a few disks to add, so maybe the better solution would > > be to add one and get the unstriped Q, then add another and let Q > > stripe with everything else during the reshape. That is, if it will > > stripe Q during the reshape. > > Your best bet would be to wait for mdadm-3.1 and do it all at once, > something like: > mdadm --grow /dev/md0 --level=raid6 --raid-disks=8 > > 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 -- 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
