Re: BTRFS Raid 5 Space missing - ideas ?

Zygo Blaxell
2019-04-22T00:09:04Z

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On Sun, Apr 21, 2019 at 07:39:59AM +0300, Andrei Borzenkov wrote:
> 20.04.2019 23:19, Adam Borowski пишет:
> > On Sat, Apr 20, 2019 at 12:46:16PM +0200, Juergen Sauer wrote:
> >> I wish a happy Easer Days before :)
> >
> > Same to you!
> >
> >> During my tests with BTRFS as Raid5 setup, I found a courious little
> >> "problem".
> >
> >> Total devices 3 FS bytes used 9.98TiB
> >> devid 1 size 9.09TiB used 4.99TiB path /dev/sdb1
> >> devid 2 size 5.46TiB used 4.99TiB path /dev/sdc1
> >> devid 3 size 5.46TiB used 4.99TiB path /dev/sde1
> >
> >> All patitioins sdb1 sdc1 sde1 are the same size: 9.0 TiB. But BTRFS ist
> >> not using the bigger space on sdc1, sde1, there is only 5.46 TiB used,
> >> even there are 9.0 Tib Avaible, so 4.0 TiB are unused.
> >
> > It's working as expected: while btrfs does RAID per block group rather than
> > per whole block device, there's no way to place a raid5 block group in a way
> > that doesn't require at least 3 devices. This means with a 3-disk setup the
> > space utilized will be only as big as the smallest one.
> >
>
> But as reported, all drives were replaced by larger ones but only one
> drive shows increased size: "All patitioins sdb1 sdc1 sde1 are the same
> size".

Did you do:

btrfs fi resize 2:max /path/to/fs
btrfs fi resize 3:max /path/to/fs

It looks like you only did

btrfs fi resize 1:max /path/to/fs

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