On 05/05/14 19:07, Brendan Hide wrote:
On 05/05/14 14:16, Marc MERLIN wrote:
I've just written this new page:
http://marc.merlins.org/perso/btrfs/post_2014-05-04_Fixing-Btrfs-Filesystem-Full-Problems.html
First, are there problems in it?
Second, are there other FS full issues I should mention in it?
Thanks,
Marc
"In the case above, because the filesystem is only 55% full, I can ask
balance to rewrite all chunks that are more than 55% full:
legolas:~# btrfs balance start -dusage=50 /mnt/btrfs_pool1"
"-dusage=50" will balance all chunks that are 50% *or less* used, not
more. The idea is that full chunks are better left alone while
emptyish chunks are bundled together to make new full chunks, leaving
big open areas for new chunks. Your process is good however - just the
explanation that needs the tweak. :)
In your last example, a full rebalance is not necessary. If you want
to clear all unnecessary chunks you can run the balance with
-dusage=80 (636GB/800GB~=79%). That will cause a rebalance only of the
data chunks that are 80% and less used, which would by necessity get
about ~160GB worth chunks back out of data and available for re-use.
The issue I'm not sure of how to get through is if you can't balance
*because* of ENOSPC errors. I'd probably start scouring the mailing
list archives if I ever come across that.
Forgot this part: Also in your last example, you used "-dusage=0" and it
balanced 91 chunks. That means you had 91 empty or very-close-to-empty
chunks. ;)
--
__________
Brendan Hide
http://swiftspirit.co.za/
http://www.webafrica.co.za/?AFF1E97
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