Re: Drive won't mount, please help

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

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On 2020/9/14 上午4:56, J J wrote:
>  I’m new to a lot of this, just trying to use a NAS at home, single usb external disk, not RAID. Was working great for a few months, I’m not sure what changed today when it stopped mounting. Any advice appreciated.

Transid mismatch, and the expected transid is newer than the on-disk
transid.

This means, either btrfs has some bug that causes metadata writeback not
following COW, or the disk controller/disk itself ignores Flush/FUA
commands.

Considering it's usb external disk, I doubt the later case.

In that case, any fs would experience similar problem if a sudden power
loss or cable loss happened.

You may workaround such problem by disabling the writecache, but I doubt
if the USB->Sata convert would follow the request.

Thanks,
Qu
> 
> Dmesg log attached
> 
> 
> uname -a
> Linux rock64 4.4.190-1233-rockchip-ayufan-gd3f1be0ed310 #1 SMP Wed Aug 28 08:59:34 UTC 2019 aarch64 GNU/Linux
> 
> 
> 
> btrfs --version
> btrfs-progs v4.7.3
> 
> 
> 
> btrfs fi show
> Label: '3TBRock64'  uuid: 71eda2e3-384c-4868-b5d4-683f222865e6
> 	Total devices 1 FS bytes used 2.48TiB
> 	devid    1 size 2.73TiB used 2.59TiB path /dev/mapper/sda-crypt
> 
> 
> btrfs fi df /dev/mapper/sda-crypt
> ERROR: not a btrfs filesystem: /dev/mapper/sda-crypt
> 
> 
> btrfs inspect-internal dump-super /dev/mapper/sda-crypt 
> superblock: bytenr=65536, device=/dev/mapper/sda-crypt
> ---------------------------------------------------------
> csum_type		0 (crc32c)
> csum_size		4
> csum			0x9e8b0c33 [match]
> bytenr			65536
> flags			0x1
> 			( WRITTEN )
> magic			_BHRfS_M [match]
> fsid			71eda2e3-384c-4868-b5d4-683f222865e6
> label			3TBRock64
> generation		395886
> root			2638934654976
> sys_array_size		129
> chunk_root_generation	377485
> root_level		1
> chunk_root		20971520
> chunk_root_level	1
> log_root		2638952366080
> log_root_transid	0
> log_root_level		0
> total_bytes		3000556847104
> bytes_used		2729422221312
> 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 )
> cache_generation	395886
> uuid_tree_generation	395886
> dev_item.uuid		b7f4386a-18e0-437b-9588-6064ff483fd5
> dev_item.fsid		71eda2e3-384c-4868-b5d4-683f222865e6 [match]
> dev_item.type		0
> dev_item.total_bytes	3000556847104
> dev_item.bytes_used	2843293515776
> 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
> 


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