On Thu, Sep 15, 2016 at 3:48 PM, Alexandre Poux <pums...@gmail.com> wrote: > > Le 15/09/2016 à 18:54, Chris Murphy a écrit : >> On Thu, Sep 15, 2016 at 10:30 AM, Alexandre Poux <pums...@gmail.com> wrote: >>> Thank you very much for your answers >>> >>> Le 15/09/2016 à 17:38, Chris Murphy a écrit : >>>> On Thu, Sep 15, 2016 at 1:44 AM, Alexandre Poux <pums...@gmail.com> wrote: >>>>> Is it possible to do some king of a "btrfs delete missing" on this >>>>> kind of setup, in order to recover access in rw to my other data, or >>>>> I must copy all my data on a new partition >>>> That *should* work :) Except that your file system with 6 drives is >>>> too full to be shrunk to 5 drives. Btrfs will either refuse, or get >>>> confused, about how to shrink a nearly full 6 drive volume into 5. >>>> >>>> So you'll have to do one of three things: >>>> >>>> 1. Add a 2+TB drive, then remove the missing one; OR >>>> 2. btrfs replace is faster and is raid10 reliable; OR >>>> 3. Read only scrub to get a file listing of bad files, then remount >>>> read-write degraded and delete them all. Now you maybe can do a device >>>> delete missing. But it's still a tight fit, it basically has to >>>> balance things out to get it to fit on an odd number of drives, it may >>>> actually not work even though there seems to be enough total space, >>>> there has to be enough space on FOUR drives. >>>> >>> Are you sure you are talking about data in single mode ? >>> I don't understand why you are talking about raid10, >>> or the fact that it will have to rebalance everything. >> Yeah sorry I got confused in that very last sentence. Single, it will >> find space in 1GiB increments. Of course this fails because that data >> doesn't exist anymore, but to start the operation it needs to be >> possible. > No problem >>> Moreover, even in degraded mode I cannot mount it in rw >>> It tells me >>> "too many missing devices, writeable remount is not allowed" >>> due to the fact I'm in single mode. >> Oh you're in that trap. Well now you're stuck. I've had the case where >> I could mount read write degraded with metadata raid1 and data single, >> but it was good for only one mount and then I get the same message you >> get and it was only possible to mount read only. At that point it's >> totally suck unless you're adept at manipulating the file system with >> a hex editor... >> >> Someone might have a patch somewhere that drops this check and lets >> too many missing devices to mount anyway... I seem to recall this. >> It'd be in the archives if it exists. >> >> >> >>> And as far as as know, btrfs replace and btrfs delete, are not supposed >>> to work in read only... >> It doesn't. Must be read write mounted. >> >> >>> I would like to tell him forgot about the missing data, and give me back >>> my partition. >> This feature doesn't exist yet. I really want to see this, it'd be >> great for ceph and gluster if the volume could lose a drive, report >> all the missing files to the cluster file system, delete the device >> and the file references, and then the cluster knows that brick doesn't >> have those files and can replicate them somewhere else or even back to >> the brick that had them. >> > So I found this patch : https://patchwork.kernel.org/patch/7014141/ > > Does this seems ok ?
No idea I haven't tried it. > > So after patching my kernel with it, > I should be able to mount in rw my partition, and thus, > I will be able to do a btrfs delete missing > Which will just forgot about the old disk and everything should be fine > afterward ? It will forget about the old disk but it will try to migrate all metadata and data that was on that disk to the remaining drives; so until you delete all files that are corrupt, you'll continue to get corruption messages about them. > > Is this risky ? or not so much ? Probably. If you care about the data, mount read only, back up what you can, then see if you can fix it after that. > The scrubing is almost finished, and as I was expecting, I lost no data > at all. Well I'd guess the device delete should work then, but I still have no idea if that patch will let you mount it degraded read-write. Worth a shot though, it'll save time. -- Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
