Re: btrfs: convert metadata from raid5 to raid1

Hugo Mills
2020-02-17T14:17:11Z

On Mon, Feb 17, 2020 at 03:12:35PM +0100, Menion wrote:
> ok thanks
> I have launched it (in a tmux session), after 5 minutes the command
> did not return yet, but dmesg and btrfs balance status
> /array/mount/point report it in progress (0%).
> Is it normal?

Yes, it's got to rewrite all of your metadata. This can take a
while (especially if you have lots of snapshots or reflinks -- such as
from running a deduper). You should be able to see progress happening
fairly regularly in dmesg. This is typically one chunk every minute or
so, although some chunks can take much *much* longer.

Hugo.

> Il giorno lun 17 feb 2020 alle ore 14:55 Swâmi Petaramesh
> <swami@petaramesh.org> ha scritto:
> >
> > On 2020-02-17 14:50, Menion wrote:
> > > Is it ok to run it on a mounted filesystem with concurrent read and
> > > write operations?
> >
> > Yes. Please check man btrfs-balance.
> >
> > All such BTRFS operations are to be run on live, mounted filesystems.
> >
> > Performance will suffer and it might be long though.
> >
> > > Also, since the number of HDD is 5, how this "raid1" scheme is deployed?
> >
> > BTRFS will manage storing 2 copies of every metadata block on 2
> > different disks, and will choose how by itself.
> >
> > ॐ
> >

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