On Wed, July 15, 2009 1:29 pm, Michael Ole Olsen wrote: > Is there any way to get anything below 2.6.30 to recognize this > 'fake' raid6 with all Q blocks on the last disk? You could back-port a selection of patches. if you git log drivers/md/raid5.c it should list all the patches you need, but it will list quite a few that you don't want as well. Or you could change the array back to raid5 by echoing "raid5" to the same place you echoed "raid6". mdadm-3.1 is making good progress but if you are getting frequent reboots, then you will really need to restart-in-the-middle -of-a-reshape functionality, and I'm not even sure the kernel side of that works yet. It'll be at least 2 weeks before I could suggest you try that. NeilBrown > > 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 >> > > >> > > Â 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. Â 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
