On 2019/12/31 下午11:04, Ole Langbehn wrote: > Hi, > > I have done three full balances in a row, each of them ending with an > error, telling me: > > BTRFS info (device nvme1n1p1): 2 enospc errors during balance > BTRFS info (device nvme1n1p1): balance: ended with status: -28 > > (first balance run it was 4 enospc errors). > > The filesystem has enough space to spare, though: > > # btrfs fi show / > Label: none uuid: 34ea0387-af9a-43b3-b7cc-7bdf7b37b8f1 > Total devices 1 FS bytes used 624.36GiB > devid 1 size 931.51GiB used 627.03GiB path /dev/nvme1n1p1 > > # btrfs fi df / > Data, single: total=614.00GiB, used=613.72GiB > System, single: total=32.00MiB, used=112.00KiB > Metadata, single: total=13.00GiB, used=10.64GiB > GlobalReserve, single: total=512.00MiB, used=0.00B > > This is after the balances, but was about the same before the balances. > Before them, data had about 50GB diff between total and used. > > The volume contains subvolumes (/ and /home) and snapshots (around 20 > per subvolume, 40 total, oldest 1 month old). > > My questions are: > > 1. why do I get enospc errors on a device that has enough spare space? A known bug in v5.4, where extra space check in relocation doesn't match the new metadata over-commit. > 2. is this bad and if yes, how can I fix it? There are patches for that: https://patchwork.kernel.org/project/linux-btrfs/list/?series=208445 > > > > A little more (noteworthy) context, if you're interested: > > The reason I started the first balance was that a df on the filesystem > showed 0% free space: > > # df > Filesystem 1K-blocks Used Available Use% Mounted on > /dev/nvme1n1p1 976760584 655217424 0 100% / Another known bug, which we also had a patch for it: https://patchwork.kernel.org/patch/11293419/ Thanks, Qu > ... > > and a big download (chromium sources) was aborted due to "not enough > space on device". > > I monitored the first balance more closely, and right after the start, > df looked normal again, showing available blocks, but during the > balance, it flip-flopped a couple of times between again showing 0 > available bytes and showing the complement between actual size and used > bytes. I did not observe this behavior any more during balance 2 and 3, > but did not observe as closely. > > TiA for any insights and ideas on how to proceed and a healthy start > into the new year for everyone. > > > >
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