[parted-devel] Diagnosing a "loop" partition

[David Liontooth]

Joel Granados wrote:
> Does this happen with git HEAD?
>   
Thanks for responding -- I haven't tried, but I'll go that route next time.

For the record, the problem can be solved simply by running cfdisk and 
recreating the partition (default, msdos). The drive mounts and the data 
is intact; the od shows:

# od -tx1 -Ax -N512 /dev/sdac
000000 58 46 53 42 00 00 10 00 00 00 00 00 0e 8e 0d b6
000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
000020 a9 cb 0a d3 5f ca 44 a3 95 73 d4 0f 35 84 ee 8e
000030 00 00 00 00 08 00 00 04 00 00 00 00 00 00 00 80
000040 00 00 00 00 00 00 00 81 00 00 00 00 00 00 00 82
000050 00 00 00 01 03 a3 83 6e 00 00 00 04 00 00 00 00
000060 00 00 80 00 b4 a4 02 00 01 00 00 10 32 30 30 38
000070 5f 30 31 73 00 00 00 00 0c 09 08 04 1a 00 00 19
000080 00 00 00 00 00 00 00 40 00 00 00 00 00 00 00 3d
000090 00 00 00 00 0e 8d 8d a2 00 00 00 00 00 00 00 00
0000a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0000b0 00 00 00 00 00 00 00 02 00 00 00 00 00 00 00 00
0000c0 00 00 00 00 00 00 00 01 00 00 00 08 00 00 00 08
0000d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
*
0001b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01
0001c0 01 00 83 fe ff ff 3f 00 00 00 82 59 70 74 00 00
0001d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
*
0001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa
000200

Dave
> Regards.
> On Wed, Apr 15, 2009 at 08:08:44AM -0700, David Liontooth wrote:
>   
>> On an Areca controller, in JBOD mode, I used cfdisk to create a single  
>> partition, and mksf.xfs for the file system.
>>
>> On reboot, Linux 2.6.27.9 reports "unknown partition table", while  
>> parted identifies the partition table type as "loop":
>>
>> # parted /dev/sdac
>> GNU Parted 1.8.8        Using /dev/sdac
>> Welcome to GNU Parted! Type 'help' to view a list of commands.
>> (parted) print                                                            
>> Model: Seagate ST31000340NS (scsi)
>> Disk /dev/sdac: 1000GB
>> Sector size (logical/physical): 512B/512B
>> Partition Table: loop
>>
>> Number  Start  End     Size    File system  Flags
>> 1      0.00B  1000GB  1000GB  xfs              
>>
>> (parted) print 1                                                          
>> No Implementation: Support for opening xfs file systems is not  
>> implemented yet.
>>
>> An octal dump shows:
>>
>> # od -tx1 -Ax -N512 /dev/sdad
>> 000000 58 46 53 42 00 00 10 00 00 00 00 00 0e 8e 0d b6
>> 000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> 000020 06 a8 a8 db 91 f3 45 4a 84 80 87 11 62 35 93 3b
>> 000030 00 00 00 00 08 00 00 04 00 00 00 00 00 00 00 80
>> 000040 00 00 00 00 00 00 00 81 00 00 00 00 00 00 00 82
>> 000050 00 00 00 01 03 a3 83 6e 00 00 00 04 00 00 00 00
>> 000060 00 00 80 00 b4 a4 02 00 01 00 00 10 32 30 30 38
>> 000070 5f 30 33 73 00 00 00 00 0c 09 08 04 1a 00 00 19
>> 000080 00 00 00 00 00 00 00 40 00 00 00 00 00 00 00 3d
>> 000090 00 00 00 00 0e 8d 8d a2 00 00 00 00 00 00 00 00
>> 0000a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> 0000b0 00 00 00 00 00 00 00 02 00 00 00 00 00 00 00 00
>> 0000c0 00 00 00 00 00 00 00 01 00 00 00 08 00 00 00 08
>> 0000d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> *
>> 000200
>>
>> In contrast, a working drive shows:
>>
>> # parted /dev/sdaa
>> GNU Parted 1.8.8
>> Using /dev/sdaa
>> Welcome to GNU Parted! Type 'help' to view a list of commands.
>> (parted) print                                                            
>> Model: Seagate ST31000340NS (scsi)
>> Disk /dev/sdaa: 1000GB
>> Sector size (logical/physical): 512B/512B
>> Partition Table: msdos
>>
>> Number  Start   End     Size    Type     File system  Flags
>> 1      32.3kB  1000GB  1000GB  primary  xfs              
>>
>> (parted)  print 1                                                         
>> No Implementation: Support for opening xfs file systems is not  
>> implemented yet.
>>
>> The octal dump for the working drive:
>>
>> # od -tx1 -Ax -N512 /dev/sdaa
>> 000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> *
>> 0001b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01
>> 0001c0 01 00 83 fe ff ff 3f 00 00 00 82 59 70 74 00 00
>> 0001d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> *
>> 0001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa
>> 000200
>>
>> The drives with unknown partition tables are backups, and losing them  
>> would not be a disaster, but parted plausibly reports a full file system  
>> -- I have no reason to believe it's damaged.
>>
>> Is there any way to modify the claimed "loop" partition so that the OS  
>> can see it?
>>
>> Is this really a loop partition, and if so, what's its proper usage?
>>
>> Is xfs support planned for parted?
>>
>> Dave
>>
>>
>>
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>> parted-devel at lists.alioth.debian.org
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>>     
>
>