Back in September I noticed that 'sudo du -chs /mnt/storage-1' reported 887GB used and 'df -h' 920GB for this particular volume - I went on #btrfs for any suggestions, and balancing + defraging made no difference. It had no subvolumes/snapshots etc, I basically used it like a checksumed ext4fs.
Since the volume was converted from ext4, I redid it from scratch (so
made with kernel v4.1.3 or v4.1.6 on this Debian Testing machine), and
the problem went away.
After a couple of months, df reports 907GB used, whereas du says 884GB -
I currently have 8 large (1-5.5TB volumes) btrfs volumes in use,
storage-1 is the only SSD volume and the only one with this problem.
No balancing or defraging this time, it didn't make a difference before
and this is a relatively new volume.
Are there any sysadmin-level ways I can account for the ~23GB lost space?
Thanks for any help.
=========================================================
$ uname -a
Linux omega1 4.2.0-1-amd64 #1 SMP Debian 4.2.5-1 (2015-10-27) x86_64
GNU/Linux
$ btrfs --version
btrfs-progs v4.2.2
$ sudo btrfs fi usage /mnt/storage-1
Overall:
Device size: 953.87GiB
Device allocated: 932.04GiB
Device unallocated: 21.83GiB
Device missing: 0.00B
Used: 906.10GiB
Free (estimated): 45.35GiB (min: 34.43GiB)
Data ratio: 1.00
Metadata ratio: 2.00
Global reserve: 512.00MiB (used: 0.00B)
Data,single: Size:925.01GiB, Used:901.50GiB
/dev/sdb 925.01GiB
Metadata,single: Size:8.00MiB, Used:0.00B
/dev/sdb 8.00MiB
Metadata,DUP: Size:3.50GiB, Used:2.30GiB
/dev/sdb 7.00GiB
System,single: Size:4.00MiB, Used:0.00B
/dev/sdb 4.00MiB
System,DUP: Size:8.00MiB, Used:128.00KiB
/dev/sdb 16.00MiB
Unallocated:
/dev/sdb 21.83GiB
$ sudo btrfs-show-super /dev/sdb
superblock: bytenr=65536, device=/dev/sdb
---------------------------------------------------------
csum 0x7f6b70be [match]
bytenr 65536
flags 0x1
( WRITTEN )
magic _BHRfS_M [match]
fsid 27430475-c49a-4e3f-8f8d-be5c14be59db
label storage-1
generation 114344
root 683413471232
sys_array_size 226
chunk_root_generation 114251
root_level 1
chunk_root 21004288
chunk_root_level 1
log_root 683413979136
log_root_transid 0
log_root_level 0
total_bytes 1024209543168
bytes_used 971565568000
sectorsize 4096
nodesize 16384
leafsize 16384
stripesize 4096
root_dir 6
num_devices 1
compat_flags 0x0
compat_ro_flags 0x0
incompat_flags 0x161
( MIXED_BACKREF |
BIG_METADATA |
EXTENDED_IREF |
SKINNY_METADATA )
csum_type 0
csum_size 4
cache_generation 114344
uuid_tree_generation 114344
dev_item.uuid c6b32341-6300-4f21-8c3b-3d7d458c3668
dev_item.fsid 27430475-c49a-4e3f-8f8d-be5c14be59db [match]
dev_item.type 0
dev_item.total_bytes 1024209543168
dev_item.bytes_used 1000765128704
dev_item.io_align 4096
dev_item.io_width 4096
dev_item.sector_size 4096
dev_item.devid 1
dev_item.dev_group 0
dev_item.seek_speed 0
dev_item.bandwidth 0
dev_item.generation 0
=========================================================
dmesg contains a lot of information which is superfluous to btrfs and
personal, I can filter on a regex and report if necessary.
signature.asc
Description: OpenPGP digital signature
