Reported filesystem size (fs usage, df) discrepancies
Jan Engelhardt <[email protected]>
| Newsgroups | org.kernel.vger.linux-bcachefs |
|---|---|
| Message-ID | <[email protected]> |
# uname -a
Linux localhost 6.15.4-1-default #1 SMP PREEMPT_DYNAMIC Mon Jun
30 10:37:39 UTC 2025 (55e70a8) x86_64 x86_64 x86_64 GNU/Linux
[openSUSE Tumbleweed 20250701]
# bcachefs version
1.25.1
# blockdev --getsize64 /dev/disk/by-id/ata-Micron* /dev/disk/by-id/ata-MB1000*
960197124096
960197124096
960197124096
960197124096
1000204886016
1000204886016
(total: 5570 GB / 5440 GiB)
# mount UUID=... /v
# bcachefs fs usage /v | grep capacity:
capacity: 1000203091968 476934 (x2)
capacity: 960195723264 457857 (x4)
[5440 GiB]
A bit of rounding to cancel out odd disk shapes, perfectly fine.
# bcachefs fs usage /v | grep -P '(free|journal):'
free: 992384909312 473206
journal: 7813988352 3726 (x2)
free: 952685821952 454276
journal: 7501512704 3577 (x4)
[5397 GiB]
The journal takes away a bit. Understandable.
Is it always ~0.787%? Could I specify its size manually?
# bcachefs fs usage /v | head -n2
Filesystem: (uuid)
Size: 5373893950976 [5004 GiB]
How did we reportedly lose 393 GiB / 7%?
# df -BG
/dev/sdh:/dev/sdd:/dev/sda:/dev/sdb:/dev/sdf:/dev/sde 4963G 1G 4886G 1% /v
Another 41 GiB / 0.8% just went away.
=== Full(er) output ===
# cd /dev/disk/by-id; bcachefs format \
--label=ssd.ssd0 ata-Micron_5200_MTFDDAK960TDN___________26 \
--label=ssd.ssd1 ata-Micron_5200_MTFDDAK960TDN___________60 \
--label=ssd.ssd2 ata-Micron_5200_MTFDDAK960TDN___________65 \
--label=ssd.ssd3 ata-Micron_5200_MTFDDAK960TDN___________6A \
--label=hdd.hdd0 ata-MB1000GCEEK___________72 \
--label=hdd.hdd1 ata-MB1000GCEEK___________95 \
--foreground_target=ssd --promote_target=ssd --background_target=hdd
Device index: 5
Label: (none)
Version: 1.25: extent_flags
Incompatible features allowed: 1.25: extent_flags
Incompatible features in use: 0.0: (unknown version)
Version upgrade complete: 0.0: (unknown version)
Oldest version on disk: 1.25: extent_flags
...
Superblock size: 2.31 KiB/1.00 MiB
Devices: 6
Sections: members_v1,disk_groups,members_v2
Features: new_siphash,new_extent_overwrite,btree_ptr_v2,extents_above_btree_updates,btree_updates_journalled,new_varint,journal_no_flush,alloc_v2,extents_across_btree_nodes,incompat_version_field
Compat features:
Options:
block_size: 4.00 KiB
btree_node_size: 256 KiB
errors: continue [fix_safe] panic ro
write_error_timeout: 30
metadata_replicas: 1
data_replicas: 1
metadata_replicas_required: 1
data_replicas_required: 1
encoded_extent_max: 64.0 KiB
metadata_checksum: none [crc32c] crc64 xxhash
data_checksum: none [crc32c] crc64 xxhash
checksum_err_retry_nr: 3
compression: none
background_compression: none
str_hash: crc32c crc64 [siphash]
metadata_target: none
foreground_target: ssd
background_target: hdd
promote_target: ssd
erasure_code: 0
inodes_32bit: 1
shard_inode_numbers_bits: 0
inodes_use_key_cache: 1
gc_reserve_percent: 8
gc_reserve_bytes: 0 B
root_reserve_percent: 0
wide_macs: 0
promote_whole_extents: 1
acl: 1
usrquota: 0
grpquota: 0
prjquota: 0
degraded: [ask] yes very no
journal_flush_delay: 1000
journal_flush_disabled: 0
journal_reclaim_delay: 100
journal_transaction_names: 1
allocator_stuck_timeout: 30
version_upgrade: [compatible] incompatible none
nocow: 0
members_v2 (size 880):
Device: 0
Label: ssd0 (1)
UUID: d23de44c-8eab-4653-abcd-62929d6d823c
Size: 894 GiB
read errors: 0
write errors: 0
checksum errors: 0
seqread iops: 0
seqwrite iops: 0
randread iops: 0
randwrite iops: 0
Bucket size: 2.00 MiB
First bucket: 0
Buckets: 457857
Last mount: (never)
Last superblock write: 0
State: rw
Data allowed: journal,btree,user
Has data: (none)
Btree allocated bitmap blocksize: 1.00 B
Btree allocated bitmap: 0000000000000000000000000000000000000000000000000000000000000000
Durability: 1
Discard: 1
Freespace initialized: 0
Resize on mount: 0
(ssd1/ssd2/ssd3 are basically repeats)
Device: 4
Label: hdd0 (6)
UUID: 13b8f1e1-ae2b-47a6-a7e2-718d946ba1fb
Size: 932 GiB
read errors: 0
write errors: 0
checksum errors: 0
seqread iops: 0
seqwrite iops: 0
randread iops: 0
randwrite iops: 0
Bucket size: 2.00 MiB
First bucket: 0
Buckets: 476934
Last mount: (never)
Last superblock write: 0
State: rw
Data allowed: journal,btree,user
Has data: (none)
Btree allocated bitmap blocksize: 1.00 B
Btree allocated bitmap: 0000000000000000000000000000000000000000000000000000000000000000
Durability: 1
Discard: 1
Freespace initialized: 0
Resize on mount: 0
(hdd1 is a repeat)
# bcachefs fs usage /v
Size: 5373893950976
Used: 6291456
Online reserved: 0
Data type Required/total Durability Devices
btree: 1/1 1 [sdh] 1310720
btree: 1/1 1 [sdd] 1572864
btree: 1/1 1 [sda] 1835008
btree: 1/1 1 [sdb] 1572864
Btree usage:
inodes: 262144
dirents: 262144
alloc: 3670016
subvolumes: 262144
snapshots: 262144
lru: 262144
freespace: 262144
backpointers: 262144
snapshot_trees: 262144
logged_ops: 262144
accounting: 262144
hdd.hdd0 (device 4): sdf rw
data buckets fragmented
free: 992384909312 473206
sb: 2101248 2 2093056
journal: 7813988352 3726
btree: 0 0
user: 0 0
cached: 0 0
parity: 0 0
stripe: 0 0
need_gc_gens: 0 0
need_discard: 0 0
unstriped: 0 0
capacity: 1000203091968 476934
hdd.hdd1 (device 5): sde rw
data buckets fragmented
free: 992384909312 473206
sb: 2101248 2 2093056
journal: 7813988352 3726
btree: 0 0
user: 0 0
cached: 0 0
parity: 0 0
stripe: 0 0
need_gc_gens: 0 0
need_discard: 0 0
unstriped: 0 0
capacity: 1000203091968 476934
ssd.ssd0 (device 0): sdh rw
data buckets fragmented
free: 952685821952 454276
sb: 2101248 2 2093056
journal: 7501512704 3577
btree: 1310720 2 2883584
user: 0 0
cached: 0 0
parity: 0 0
stripe: 0 0
need_gc_gens: 0 0
need_discard: 0 0
unstriped: 0 0
capacity: 960195723264 457857
ssd.ssd1 (device 1): sdd rw
data buckets fragmented
free: 952685821952 454276
sb: 2101248 2 2093056
journal: 7501512704 3577
btree: 1572864 2 2621440
user: 0 0
cached: 0 0
parity: 0 0
stripe: 0 0
need_gc_gens: 0 0
need_discard: 0 0
unstriped: 0 0
capacity: 960195723264 457857
ssd.ssd2 (device 2): sda rw
data buckets fragmented
free: 952685821952 454276
sb: 2101248 2 2093056
journal: 7501512704 3577
btree: 1835008 2 2359296
user: 0 0
cached: 0 0
parity: 0 0
stripe: 0 0
need_gc_gens: 0 0
need_discard: 0 0
unstriped: 0 0
capacity: 960195723264 457857
ssd.ssd3 (device 3): sdb rw
data buckets fragmented
free: 952685821952 454276
sb: 2101248 2 2093056
journal: 7501512704 3577
btree: 1572864 2 2621440
user: 0 0
cached: 0 0
parity: 0 0
stripe: 0 0
need_gc_gens: 0 0
need_discard: 0 0
unstriped: 0 0
capacity: 960195723264 457857