On Wed, Feb 03, 2010 at 08:43:58PM -0600, Mitch Harder wrote: > I've been trying to get a handle on where my Btrfs partition would run > out of room, and I'm reaching the 'no space left' point earlier than I > was expecting. > > I'm running the btrfs-unstable.git version as of commit 035fe03a Thu, > 28 Jan 2010 21:20:39 (Btrfs: check total number of devices when > removing missing) back-ported to a 2.6.32 kernel. > > Also, I've manually added Josef Bacik's 'btrfsctl -i' patches to get > more information about the state when full. > > I'm using a single 13.4GB partition as a root partition for a Sabayon > Linux system. With the btrfs file system ~59% full, I booted to > another partition, and filled the remainder of the space using 'dd' > (dd if=/dev/urandom of=/<path-to-btrfs-mounted-partition>/randomdata > bs=1024k) to see where I'd get a full-disk error. > > A btrfs 'no space left' error is received with the 'df' command > showing only 81% full. > > 'df -T' reports: > Filesystem Type 1K-blocks Used Available Use% Mounted on > /dev/sda5 btrfs 14008648 11314552 2694096 81% /mnt/sabayon-btrfs > > The dmesg disk full error reported: > [ 1606.386085] no space left, need 1048576, 89128960 delalloc bytes, > 10639556608 bytes_used, 3981312 bytes_reserved, 0 bytes_pinned, > 0 bytes_readonly, 0 may use 10733551616 total > > Josef Bacik's 'btrfsctl -i' command reported: > # btrfsctl -i /mnt/sabayon-btrfs/ > Metadata, DUP: total=1.67GB, used=813.89MB > System, DUP: total=8.00MB, used=4.00KB > Data: total=10.00GB, used=10.00GB > Metadata: total=8.00MB, used=0.00 > System: total=4.00MB, used=0.00 > operation complete > Btrfs Btrfs v0.19 > > Using 'btrfsctl -i', I'm still having trouble closing the loop on disk > utilization. 10.00 GB Data + 1.67 GB Metadata = 11.67GB. Since this > is a 13.4GB partition, I'm still missing ~1.7GB, based on the > 'btrfsctl -i' reporting. > > Is 1.67 GB reserved for Metadata about what might be expected for a > messy root partition with ~10GB of files?
Sorry I guess I should have fixed df -i to print the actual disk space used. Anything with 'DUP' as the identifier means you need to take the totals it gives you and multiply by 2, because all that data is duplicated. So in your case you have > Metadata, DUP: total=1.67GB, used=813.89MB > System, DUP: total=8.00MB, used=4.00KB So really you have 3.34 gb total disk space reserved for metadata, and you are using 1.58 gb of that total space. Same goes for System, you really have 16 mb reserved and are using 8 kb. Now if you don't want to use the metadata duplication feature of btrfs, then you can do mkfs.btrfs -m single /dev/whatever and you won't end up with duplicate metadata. Thanks, Josef -- 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
