Interesting. I've always noticed that value to be fairly close to the total drive size, so I just assumed it was supposed to match.
Thanks! Jeremy On Sun, Oct 9, 2016 at 5:08 PM, Hugo Mills <h...@carfax.org.uk> wrote: > On Sun, Oct 09, 2016 at 04:59:04PM -0400, Jeremy Yoder wrote: >> I didn't notice this until it was nearly too late. I had run out of >> metadata space so I ran >> btrfs balance start -v -dusage=0 /mnt/btrfsroot >> >> That went fine, but I was still low on metadata space, so I tried a >> few variations: >> btrfs balance start -v -dusage=1 /mnt/btrfsroot >> btrfs balance start -v -dusage=5 /mnt/btrfsroot >> btrfs balance start -v -dusage=10 /mnt/btrfsroot >> >> I didn't run any of these to completion, I cancelled them after a few hours. >> >> I captured the output of a couple commands every once in a while: >> btrfs fi df /mnt/btrfsroot >> btrfs fi show /dev/sda5 >> >> What I didn't notice (because I was looking at the metadata space) was >> the Data total size. >> >> It starts out as: >> >> Data, single: total=4.61TiB, used=2.50TiB >> System, DUP: total=8.00MiB, used=576.00KiB >> System, single: total=4.00MiB, used=0.00 >> Metadata, DUP: total=46.50GiB, used=42.82GiB >> Metadata, single: total=8.00MiB, used=0.00 >> unknown, single: total=512.00MiB, used=0.00 >> >> Label: none uuid: e6818780-7d28-41fe-b7a8-e38b61a98621 >> Total devices 1 FS bytes used 2.54TiB >> devid 1 size 5.35TiB used 4.70TiB path /dev/sda5 >> >> Over time however, the Data total begins to drop: >> Data, single: total=4.56TiB, used=2.50TiB >> Data, single: total=4.41TiB, used=2.50TiB >> Data, single: total=4.23TiB, used=2.51TiB >> Data, single: total=4.00TiB, used=2.51TiB >> Data, single: total=3.59TiB, used=2.51TiB >> Data, single: total=3.35TiB, used=2.51TiB >> >> The drop corresponds to a drop in the "show" used amounts: >> devid 1 size 5.35TiB used 4.65TiB path /dev/sda5 >> devid 1 size 5.35TiB used 4.50TiB path /dev/sda5 >> devid 1 size 5.35TiB used 4.32TiB path /dev/sda5 >> devid 1 size 5.35TiB used 4.09TiB path /dev/sda5 >> devid 1 size 5.35TiB used 3.68TiB path /dev/sda5 >> devid 1 size 5.35TiB used 3.44TiB path /dev/sda5 >> >> System info: >> Ubuntu 14.04 >> Linux server4 4.4.0-38-generic #57~14.04.1-Ubuntu SMP Tue Sep 6 >> 17:20:43 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux >> >> I had been running the 14.04 btrfs-progs version 3.12-1ubuntu0.1 >> >> I just upgraded to btrfs-progs 4.4.1~ubuntu14.04.1~ppa1 from a PPA, >> which allowed me to run >> # btrfs fi usage /mnt/btrfsroot/ >> Overall: >> Device size: 5.35TiB >> Device allocated: 3.44TiB >> Device unallocated: 1.91TiB >> Device missing: 0.00B >> Used: 2.59TiB >> Free (estimated): 2.75TiB (min: 1.80TiB) >> Data ratio: 1.00 >> Metadata ratio: 2.00 >> Global reserve: 512.00MiB (used: 0.00B) >> >> Data,single: Size:3.35TiB, Used:2.51TiB >> /dev/sda5 3.35TiB >> >> Metadata,DUP: Size:46.50GiB, Used:42.07GiB >> /dev/sda5 93.00GiB >> >> System,DUP: Size:32.00MiB, Used:416.00KiB >> /dev/sda5 64.00MiB >> >> Unallocated: >> /dev/sda5 1.91TiB >> >> Any suggestions? > > Do nothing. The FS is working as designed. :) > > The "Data, total" value you're worried about is the amount of space > currently allocated for use as data. The balance operation takes a > chunk of data allocation, and moves any data in it to other chunks. > Once the chunk is empty, it's freed up. Now, when the data is moved, > it will typically go to any free allocated space first; only if there > isn't any free space allocated for data will more space be allocated. > So, the normal behaviour is that when you run a balance, the data is > effectively compacted into fewer chunks, and the unused chunks are > freed up. If the FS needs more chunks allocated, it will do so > automatically, so you're not losing anything here. > > Hugo. > > -- > Hugo Mills | You know... I'm sure this code would seem a lot > hugo@... carfax.org.uk | better if I never tried running it. > http://carfax.org.uk/ | > PGP: E2AB1DE4 | -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
