Confusing output of btrfs fi df

Hello

Chris and Duncan: I tried both your suggestions but unfortunately without success. Here is the output:

mars:~ # btrfs balance start -susage=0 -f -v /mnt/btrfs/ Dumping filters: flags 0xa, state 0x0, force is on
SYSTEM (flags 0x2): balancing, usage=0
Done, had to relocate 0 out of 2708 chunks

mars:~ # btrfs fi df /mnt/btrfs/
Data, RAID1: total=2.64TiB, used=2.22TiB
System, RAID1: total=8.00MiB, used=380.00KiB
System, single: total=4.00MiB, used=0.00
Metadata, RAID1: total=4.00GiB, used=2.94GiB
--------------------------------------------

mars:~ # btrfs balance start -sconvert=raid1,soft -f -v /mnt/btrfs/ Dumping filters: flags 0xa, state 0x0, force is on
SYSTEM (flags 0x300): converting, target=16, soft is on Done, had to relocate 0 out of 2708 chunks

mars:~ # btrfs fi df /mnt/btrfs/
Data, RAID1: total=2.64TiB, used=2.22TiB
System, RAID1: total=8.00MiB, used=380.00KiB
System, single: total=4.00MiB, used=0.00
Metadata, RAID1: total=4.00GiB, used=2.94GiB

Yours sincerely
Stefan

Stefan Malte Schumacher posted on Sun, 27 Apr 2014 17:37:26 +0200 as excerpted:

OK, this is interesting It may be that you're reproducing something a couple other people saw earlier, but I've never seen here, which might be because I tend to do -m<whatever (metadata) and let it handle -s/system at the same time, instead of doing -s<whatever> explicitly.

So try this one:

btrfs balance start -musage=0 -v

(-f shouldn't be needed for this one because you're not doing -s specifically, and not forcing a lower redundancy level.)

It may or may not free a couple metadata chunks too, but at least here, that's /exactly/ what I've used, and it has /never/ failed to cleanup that unused system chunk.

If that fails to remove the extra system chunk, then we have a mystery indeed. What's different on your system and why isn't it working?

If it succeeds in removing it, then we have a different and more limited bug/mystery. -s sometimes ignores system chunks it's documented to balance, while -m is doing both metadata and system, as expected.

Duncan - List replies preferred.   No HTML msgs.
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