Help with a little dd damage!

Jacques B. jjrboucher at
Thu Feb 28 01:06:51 UTC 2008

>  he copied 1280 blocks .... then overwrote it with 2348 blocks ... the
>  damage is done

No.  Look at his output:
[root at morgansmachine DiskBUImagesEtc]# dd if=/dev/sda of=pocketpc.rescue
bs=1M count=33
(No output, just bash history.)

Today I ran these commands:
[root at morgansmachine DiskBUImagesEtc]# dd if=/dev/sda of=2ndstage.rescue
bs=1K count=1280
1280+0 records in
1280+0 records out
1310720 bytes (1.3 MB) copied, 0.0535238 s, 24.5 MB/s
[root at morgansmachine DiskBUImagesEtc]# chown morgan: ./2ndstage.rescue
[root at morgansmachine DiskBUImagesEtc]# dd
2348+0 records in
2348+0 records out
1202176 bytes (1.2 MB) copied, 0.117155 s, 10.3 MB/s

1st action:  33 megs was from /dev/sda to a file.
2nd action: 1.3 MB from /dev/sda to a file
3rd action: 1.2 MB from a file to /dev/sda

So he backed up 1.3 MB to a file, then overwrote 1.2MB.  So restoring
1.2MB of that original backup will restore that part of /dev/sda to
it's previous status.

Jacques B.

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