Thomas Kuther
2014-Jan-12 20:24 UTC
Issues with "no space left on device" maybe related to 3.13 and/or kvm disk image fragmentation
Hello, I'm experiencing an interesting issue with the BTRFS filesystem on my SSD drive. It first occured some time after the upgrade to kernel 3.13-rc (-rc3 was my first 3.13-rc) but I'm not sure if it is related. The obvious symptoms are that services on my system started crashing with "no space left on device" errors. └» mount |grep "/mnt/ssd" /dev/sda2 on /mnt/ssd type btrfs (rw,noatime,compress=lzo,ssd,noacl,space_cache) └» btrfs fi df /mnt/ssd Data, single: total=113.11GiB, used=90.02GiB System, DUP: total=64.00MiB, used=24.00KiB System, single: total=4.00MiB, used=0.00 Metadata, DUP: total=3.00GiB, used=2.46GiB I use snapper on two subvolumes of that BTRFS volume (/ and /home) - each keeping 7 daily snapshots and up to 10 hourlys. When I saw those errors I started to delete most of the older snapshots, and the issue went away instantly, but this couldn't be a solution nor a workaround. I do though have a "usual suspect" on that BTRFS volume. A KVM disk image of a Win8 VM (I _need_ Adobe Lightroom) » lsattr /mnt/ssd/kvm-images/ ---------------C /mnt/ssd/kvm-images/Windows_8_Pro.qcow2 So the image has CoW disabled. Now comes the interesting part: I'm trying to copy off the image to my raid5 array (BTRFS ontop of a mdraid 5 - absolutely no issues with that one), but the cp process seems like it's stalled. After one hour the size of the destination copy is still 0 bytes. iotop almost constantly show values like TID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 4636 be/4 tom 14.40 K/s 0.00 B/s 0.00 % 0.71 % cp /mnt/ssd/kvm-images/Windows_8_Pro.qcow2 . It tries to read the file with some 14K/s and writes absolutely nothing. Any idea what's going wrong here, or suggestions how to get that qcow file copied off? I do have a backup, but honestly that one is quite aged - so simply rm'ing it would be the very last thing I'd like to try. Regards, Tom PS: please reply-to-all, I'm not subscribed. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html