Hello,
I've backed-up my two disks /dev/sda and /dev/sdb onto a big external
harddrive:
-rw-r--r-- 1 root root 320072933376 2008-06-15 23:13 sda_atlantis_20080615
-rw-r--r-- 1 root root 320072933376 2008-06-16 02:43 sdb_atlantis_20080615
I map the disk images onto loop devices:
losetup -f -v sda_atlantis_20080615
losetup -f -v sdb_atlantis_20080615
Now I am trying to access the data. As I was not successful to make
dmraid recognize the raid array on the loop devices /dev/loop0 and
/dev/loop1 I am trying my luck directly with dmsetup.
I know the device mapper table structure, e.g. "dmsetup table" on the
original machine says:
isw_bjebjjjbd_RAID_Volume03: 0 4176900 linear 254:0 610389675
isw_bjebjjjbd_RAID_Volume02: 0 610375680 linear 254:0 2048
isw_bjebjjjbd_RAID_Volume0: 0 1250275840 striped 2 256 8:0 0 8:16 0
isw_bjebjjjbd_RAID_Volume05: 0 42012672 linear 254:0 1208258560
isw_bjebjjjbd_RAID_Volume04: 0 593682075 linear 254:0 614566575
I would be interested in the data on "isw_bjebjjjbd_RAID_Volume04".
Therefore I create a file "table.txt":
0 1250275840 striped 2 256 /dev/loop0 0 /dev/loop1 0
and execute:
dmsetup create test table.txt
Then I create the file "table1.txt"
0 593682075 linear /dev/mapper/test 614566575
and execute:
dmsetup create test4 table1.txt
After that "dmsetup table" correctly shows me the created dm devices,
but I cannot mount the test4 device.
# file -s /dev/mapper/test
/dev/mapper/test: x86 boot sector; partition 2: ID=0x7, active,
starthead 32, startsector 2048, 610375680 sectors; partition 3: ID=0x82,
starthead 254, startsector 610389675, 4176900 sectors; partition 4:
ID=0x83, starthead 254, startsector 614566575, 593682075 sectors, code
offset 0x48
# file -s /dev/mapper/test4
/dev/mapper/test4: ERROR: cannot read `/dev/mapper/test4' (Input/output
error)
# fdisk /dev/mapper/test
The number of cylinders for this disk is set to 77826.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Unable to read /dev/mapper/test
Would anybody on this list have some recommendation on how to access the
data on the dumped disk images? How can I mage dmraid recognize the raid
array on loop0 and loop1?
# dmraid -b /dev/loop0 /dev/loop1
no block devices found
Many thanks,
--
Christian Schuhegger
http://www.el-chef.de/
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