bcachefs
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koverstreet
Mark virtualbox vdi as --nocow will cause vm hang
I first observed this phenomenon on 6.14, but I thought it caused by file migration,. Until I just reinstalled a Win11 vm and tried to shutdown after marking vdi as nocow, I immediately reproduced the problem
Device: ST4000VX000-2AG1
External UUID: f66dffe7-7b1a-49d6-a8be-69ef895729ab
Internal UUID: 75af672c-d0b4-4d68-9655-32d2eae6a53b
Magic number: c68573f6-66ce-90a9-d96a-60cf803df7ef
Device index: 1
Label: (none)
Version: 1.25: extent_flags
Incompatible features allowed: 0.0: (unknown version)
Incompatible features in use: 0.0: (unknown version)
Version upgrade complete: 1.25: extent_flags
Oldest version on disk: 1.3: rebalance_work
Created: Mon Mar 4 20:45:32 2024
Sequence number: 1444
Time of last write: Sat Jun 14 08:56:26 2025
Superblock size: 5.49 KiB/1.00 MiB
Clean: 0
Devices: 4
Sections: members_v1,replicas_v0,disk_groups,clean,journal_seq_blacklist,journal_v2,counters,members_v2,errors,ext,downgrade
Features: zstd,journal_seq_blacklist_v3,reflink,new_siphash,inline_data,new_extent_overwrite,btree_ptr_v2,extents_above_btree_updates,btree_updates_journalled,reflink_inline_data,new_varint,journal_no_flush,alloc_v2,extents_across_btree_nodes
Compat features: alloc_info,alloc_metadata,extents_above_btree_updates_done,bformat_overflow_done
Options:
block_size: 4.00 KiB
btree_node_size: 256 KiB
errors: continue [fix_safe] panic ro
write_error_timeout: 30
metadata_replicas: 3
data_replicas: 2
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: zstd
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: 4
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 592):
Device: 0
Label: ssd1 (1)
UUID: 75b2480d-a622-4450-8e62-a29b7144c5e4
Size: 477 GiB
read errors: 0
write errors: 0
checksum errors: 0
seqread iops: 0
seqwrite iops: 0
randread iops: 0
randwrite iops: 0
Bucket size: 256 KiB
First bucket: 0
Buckets: 1953545
Last mount: Sat Jun 14 08:55:35 2025
Last superblock write: 1444
State: rw
Data allowed: journal,btree,user
Has data: journal,btree,user,cached
Btree allocated bitmap blocksize: 16.0 MiB
Btree allocated bitmap: 0000001111111111111111111111111111111111111111111111111111111111
Durability: 1
Discard: 0
Freespace initialized: 1
Resize on mount: 0
Device: 1
Label: hdd1 (3)
UUID: 747422f2-6b4b-4e00-a40b-d4012fb99419
Size: 3.64 TiB
read errors: 0
write errors: 0
checksum errors: 0
seqread iops: 0
seqwrite iops: 0
randread iops: 0
randwrite iops: 0
Bucket size: 256 KiB
First bucket: 0
Buckets: 15261791
Last mount: Sat Jun 14 08:55:35 2025
Last superblock write: 1444
State: rw
Data allowed: journal,btree,user
Has data: journal,btree,user,cached
Btree allocated bitmap blocksize: 32.0 MiB
Btree allocated bitmap: 0000000000000001111111111111111111111111111111111111111111111111
Durability: 1
Discard: 0
Freespace initialized: 1
Resize on mount: 0
Device: 2
Label: hdd2 (4)
UUID: 4e62e3cb-3786-4a81-b22a-41af3a40ecec
Size: 2.73 TiB
read errors: 0
write errors: 0
checksum errors: 0
seqread iops: 0
seqwrite iops: 0
randread iops: 0
randwrite iops: 0
Bucket size: 1.00 MiB
First bucket: 0
Buckets: 2861588
Last mount: Sat Jun 14 08:55:35 2025
Last superblock write: 1444
State: rw
Data allowed: journal,btree,user
Has data: journal,btree,user,cached
Btree allocated bitmap blocksize: 16.0 MiB
Btree allocated bitmap: 0000000000011111111111111111111111111111111111111111111111111111
Durability: 1
Discard: 0
Freespace initialized: 1
Resize on mount: 0
Device: 3
Label: hdd3 (5)
UUID: 8b214b91-e2e7-45aa-9e81-8db64deb23d7
Size: 2.73 TiB
read errors: 0
write errors: 0
checksum errors: 0
seqread iops: 0
seqwrite iops: 0
randread iops: 0
randwrite iops: 0
Bucket size: 1.00 MiB
First bucket: 0
Buckets: 2861588
Last mount: Sat Jun 14 08:55:35 2025
Last superblock write: 1444
State: rw
Data allowed: journal,btree,user
Has data: journal,btree,user,cached
Btree allocated bitmap blocksize: 16.0 MiB
Btree allocated bitmap: 0000000000000000000000001001001111111111111111111111111111111111
Durability: 1
Discard: 0
Freespace initialized: 1
Resize on mount: 0
errors (size 56):
journal_entry_replicas_not_marked 4 Thu May 29 19:28:53 2025
btree_bitmap_not_marked 2 Thu Jun 6 21:31:37 2024
accounting_key_version_0 14 Sat Nov 23 12:43:38 2024
$ getfattr -R -d -m '' -- .
# file: win11.vdi
bcachefs.nocow="1"
bcachefs_effective.nocow="1"
dmesg:
vbox config and log:
