On Sat, May 5, 2012 at 10:52 PM, Hugo Mills <hugo@xxxxxxxxxxxxx> wrote: > On Sat, May 05, 2012 at 10:37:01PM +1000, Mike Sampson wrote: >> Hello list, >> >> recently reformatted my home partition from XFS to RAID1 btrfs. I used >> the default options to mkfs.btrfs except for enabling raid1 for data >> as well as metadata. Filesystem is made up of two 1TB drives. >> >> mike@mercury (0) pts/3 ~ $ sudo btrfs filesystem show >> Label: none uuid: f08a8896-e03e-4064-9b94-9342fb547e47 >> Total devices 2 FS bytes used 888.06GB >> devid 1 size 931.51GB used 931.51GB path /dev/sdb1 >> devid 2 size 931.51GB used 931.49GB path /dev/sdc1 >> >> Btrfs Btrfs v0.19 >> >> mike@mercury (0) pts/3 ~ $ btrfs filesystem df /home >> Data, RAID1: total=893.48GB, used=886.60GB >> Data: total=8.00MB, used=0.00 >> System, RAID1: total=8.00MB, used=136.00KB >> System: total=4.00MB, used=0.00 >> Metadata, RAID1: total=38.00GB, used=2.54GB >> Metadata: total=8.00MB, used=0.00 >> >> As can be seen I don't have a lot of free space left and while I am >> planning on adding more storage soon I would like to gain a little >> breathing room until I can do this. While I don't have a lot of space >> remaining in Data, RAID1 I do have a good chunk in Metadata, RAID1. >> 2.5GB used out of 38GB. Does this excess become available >> automatically to the file system when the block groups in Data, RAID1 >> are exhausted or, if not, is there a way to manually reallocate them? > > Youre best bet at the moment is to try a partial balance of > metadata chunks: > > # btrfs balance start -m /home > > That will rewrite all of your metadata, putting it through the > allocator again, and removing the original allocated chunks. This > should have the effect of reducing the allocation of metadata chunks. > > You will need a 3.3 kernel, or later, and an up-to-date userspace > from cmason's git repository. Gave this a shot and it did help. mike@mercury (0) pts/3 ~/.../btrfs-progs git:master $ uname -r 3.3.4-2-ARCH mike@mercury (0) pts/3 ~/.../btrfs-progs git:master $ sudo ./btrfs balance start -m /home Done, had to relocate 40 out of 934 chunks mike@mercury (0) pts/3 ~/.../btrfs-progs git:master $ ./btrfs filesystem df /home Data, RAID1: total=900.97GB, used=880.06GB Data: total=8.00MB, used=0.00 System, RAID1: total=32.00MB, used=136.00KB System: total=4.00MB, used=0.00 Metadata, RAID1: total=30.50GB, used=2.54GB There is now 8GB less in Metadata and I was able to delete some files as well to free up space. There is still a lot of wasted space in the metadata block groups. It seems that it allocates more metadata block groups than required for my filesystem. This will do until I am able to add a couple of devices to the system. Is there anyway to adjust the block group allocation strategy at filesystem creation? Thanks Hugo, Mike -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
