Re: Data single *and* raid?

[Hugo Mills <hugo@carfax.org.uk>]

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On Sun, Aug 02, 2015 at 12:31:13PM -0600, Chris Murphy wrote:
> On Sat, Aug 1, 2015 at 9:46 PM, Duncan <1i5t5.duncan@cox.net> wrote:
> 
> > If it was setup with something earlier (not sure about 4.1.0, was it
> > affected?
> 
> No.
> 
> > but 4.0.x and earlier should be fine for setup), however, once
> > on a new kernel the usual ENOSPC workarounds can be given a try.  That
> > would include a first balance start -dusage=0 -musage=0, and if that
> > didn't free up at least a gig on a second device,
> 
> If I'm following this correctly, the reproduce steps would be to
> create a single device Btrfs that's ~94% full, add two devices, then
> convert to raid5. I think what's going on here is empty single profile
> data chunks aren't being deallocated, and it's effectively a 2 device
> raid5.

   This isn't supported by the btrfs fi df output: all of the
allocated space is used.

   Hugo.

> So actually, you're right, either -dusage=0 might fix it, or better,
> newer kernel that automatically deallocated empty/converted single
> profile data chunks. But right now it will take another balance in the
> end because it looks like this is effectively a 2 device raid5, with
> the 3rd drive full of single only chunks (which might be empty?).

-- 
Hugo Mills             | I'll take your bet, but make it ten thousand francs.
hugo@... carfax.org.uk | I'm only a _poor_ corrupt official.
http://carfax.org.uk/  |
PGP: E2AB1DE4          |                              Capt. Renaud, Casablanca

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