* dd does it again!
@ 2019-11-11 2:44 Paul Monsour
2019-11-11 5:19 ` Anand Jain
2019-11-11 19:19 ` Chris Murphy
0 siblings, 2 replies; 3+ messages in thread
From: Paul Monsour @ 2019-11-11 2:44 UTC (permalink / raw)
To: linux-btrfs
Hi,
I did it; I used dd and accidentally zapped all of my personal files, which were under the /home directory. This was a btrfs raid0 setup with /dev/sdc1 and /dev/sdd1. I aborted the command after it had started but before it had completed. Neither directory is now mountable, but btrfs fi show produced the following output:
[root@sysresccd /]# btrfs fi show
Label: none uuid: 9819165f-fade-471a-9f93-86f36523e58a
Total devices 1 FS bytes used 28.81GiB
devid 1 size 48.82GiB used 32.02GiB path /dev/sdb1
warning, device 2 is missing
Label: none uuid: 9985ee11-bc6d-4f06-ab15-3156457ba29c
Total devices 1 FS bytes used 32.75GiB
devid 1 size 58.59GiB used 45.06GiB path /dev/sdb5
Label: none uuid: 073f1926-d84d-4150-9498-4239b5383272
Total devices 2 FS bytes used 629.10GiB
devid 1 size 2.73TiB used 646.12GiB path /dev/sdc1
*** Some devices missing
parted -l produced:
Model: ATA ST3000DM008-2DM1 (scsi)
Disk /dev/sdc: 3001GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name Flags
1 1049kB 3001GB 3001GB btrfs Home
Model: ATA ST3000DM008-2DM1 (scsi)
Disk /dev/sdd: 3001GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos
Disk Flags:
Number Start End Size Type File system Flags
2 119kB 1593kB 1475kB primary esp
The portion of the dd command that wrecked the files was "of=/dev/sdd1"
btrfs restore produced just:
drwxr-xr-x 1 root root 0 Nov 10 12:43 ftp
drwxr-xr-x 1 root root 362 Nov 10 12:51 palsor
However, I was (perhaps optimistically) heartened by what "btrfs-find-root /dev/sdc1" produced:
# btrfs-find-root /dev/sdc1
warning, device 2 is missing
Superblock thinks the generation is 322292
Superblock thinks the level is 1
Found tree root at 649710272512 gen 322292 level 1
How do I use this information? Is there reason to be optimistic?
Thanks in advance for your help.
Paul Monsour
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: dd does it again!
2019-11-11 2:44 dd does it again! Paul Monsour
@ 2019-11-11 5:19 ` Anand Jain
2019-11-11 19:19 ` Chris Murphy
1 sibling, 0 replies; 3+ messages in thread
From: Anand Jain @ 2019-11-11 5:19 UTC (permalink / raw)
To: Paul Monsour, linux-btrfs
On 11/11/19 10:44 AM, Paul Monsour wrote:
> Hi,
>
> I did it; I used dd and accidentally zapped all of my personal files, which were under the /home directory. This was a btrfs raid0 setup with /dev/sdc1 and /dev/sdd1. I aborted the command after it had started but before it had completed. Neither directory is now mountable, but btrfs fi show produced the following output:
>
> [root@sysresccd /]# btrfs fi show
> Label: none uuid: 9819165f-fade-471a-9f93-86f36523e58a
> Total devices 1 FS bytes used 28.81GiB
> devid 1 size 48.82GiB used 32.02GiB path /dev/sdb1
> warning, device 2 is missing
> Label: none uuid: 9985ee11-bc6d-4f06-ab15-3156457ba29c
> Total devices 1 FS bytes used 32.75GiB
> devid 1 size 58.59GiB used 45.06GiB path /dev/sdb5
> Label: none uuid: 073f1926-d84d-4150-9498-4239b5383272
> Total devices 2 FS bytes used 629.10GiB
> devid 1 size 2.73TiB used 646.12GiB path /dev/sdc1
> *** Some devices missing
>
> parted -l produced:
>
> Model: ATA ST3000DM008-2DM1 (scsi)
> Disk /dev/sdc: 3001GB
> Sector size (logical/physical): 512B/4096B
> Partition Table: gpt
> Disk Flags:
> Number Start End Size File system Name Flags
> 1 1049kB 3001GB 3001GB btrfs Home
>
> Model: ATA ST3000DM008-2DM1 (scsi)
> Disk /dev/sdd: 3001GB
> Sector size (logical/physical): 512B/4096B
> Partition Table: msdos
> Disk Flags:
> Number Start End Size Type File system Flags
> 2 119kB 1593kB 1475kB primary esp
>
> The portion of the dd command that wrecked the files was "of=/dev/sdd1"
btrfs keeps 2 or 3 copies of superblock depending on the disk size,
you could try recover superblock from the backup superblock, but
first try to read all the superblocks using the command..
btrfs inspect-internal dump-super -a <dev>
And if there is any superblock copy which is still not overwritten.
you can recover using..
btrfs rescue super-recover [options] <device>
But depending on the extent of the accidental overwrite on the
RAID0, there is slim chances to recover the data and metadata.
HTH.
Thanks, Anand
>
> btrfs restore produced just:
>
> drwxr-xr-x 1 root root 0 Nov 10 12:43 ftp
> drwxr-xr-x 1 root root 362 Nov 10 12:51 palsor
>
> However, I was (perhaps optimistically) heartened by what "btrfs-find-root /dev/sdc1" produced:
>
> # btrfs-find-root /dev/sdc1
> warning, device 2 is missing
> Superblock thinks the generation is 322292
> Superblock thinks the level is 1
> Found tree root at 649710272512 gen 322292 level 1
>
> How do I use this information? Is there reason to be optimistic?
>
> Thanks in advance for your help.
>
> Paul Monsour
>
>
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: dd does it again!
2019-11-11 2:44 dd does it again! Paul Monsour
2019-11-11 5:19 ` Anand Jain
@ 2019-11-11 19:19 ` Chris Murphy
1 sibling, 0 replies; 3+ messages in thread
From: Chris Murphy @ 2019-11-11 19:19 UTC (permalink / raw)
To: Paul Monsour; +Cc: Btrfs BTRFS
On Mon, Nov 11, 2019 at 2:44 AM Paul Monsour <boulos@gmx.com> wrote:
>
> parted -l produced:
>
> Model: ATA ST3000DM008-2DM1 (scsi)
> Disk /dev/sdc: 3001GB
> Sector size (logical/physical): 512B/4096B
> Partition Table: gpt
> Disk Flags:
> Number Start End Size File system Name Flags
> 1 1049kB 3001GB 3001GB btrfs Home
>
> Model: ATA ST3000DM008-2DM1 (scsi)
> Disk /dev/sdd: 3001GB
> Sector size (logical/physical): 512B/4096B
> Partition Table: msdos
> Disk Flags:
> Number Start End Size Type File system Flags
> 2 119kB 1593kB 1475kB primary esp
>
> The portion of the dd command that wrecked the files was "of=/dev/sdd1"
OK? According to the parted output, there is a single partition number
2, therefore only /dev/sdd2 should exist and the dd command should
have failed. So... something is missing in the information provided,
or maybe a typo somewhere.
>
> btrfs restore produced just:
>
> drwxr-xr-x 1 root root 0 Nov 10 12:43 ftp
> drwxr-xr-x 1 root root 362 Nov 10 12:51 palsor
>
> However, I was (perhaps optimistically) heartened by what "btrfs-find-root /dev/sdc1" produced:
>
> # btrfs-find-root /dev/sdc1
> warning, device 2 is missing
> Superblock thinks the generation is 322292
> Superblock thinks the level is 1
> Found tree root at 649710272512 gen 322292 level 1
>
> How do I use this information? Is there reason to be optimistic?
No. The best possible case is data raid0, and metadata raid1, in which
case the file system will mount with "degraded" option and you'll be
able to recover any files that are completely on the intact device,
and not subject to any striping. Otherwise they will be considered by
Btrfs to be corrupt/missing, although I'm not sure if it results in
EIO or something else. If metadata is also raid0, then the file system
won't mount. You probably also won't have much success with btrfs
restore either.
--
Chris Murphy
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2019-11-11 19:19 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-11-11 2:44 dd does it again! Paul Monsour
2019-11-11 5:19 ` Anand Jain
2019-11-11 19:19 ` Chris Murphy
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).