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shred and odd partition sizes
From: |
Bruno Haible |
Subject: |
shred and odd partition sizes |
Date: |
Fri, 18 Aug 2006 19:51:41 +0200 |
User-agent: |
KMail/1.9.1 |
Hi,
I'm using shred-4.5.7 to clean disk partitions. Often a partition has an odd
number of 512-byte blocks; Linux fdisk indicates such partitions with a '+'.
Shred, when used on such a partition, gives three error messages:
attempt to access beyond end of device
03:06: rw=0, want=4200968, (=0x401a08), limit=4200966
attempt to access beyond end of device
03:06: rw=0, want=4200968, (=0x401a08), limit=4200966
/usr/bin/shred: /dev/hda6: error writing at offset 4301787136: Input/output
error
attempt to access beyond end of device
03:06: rw=0, want=4200968, (=0x401a08), limit=4200966
/usr/bin/shred: /dev/hda6: error writing at offset 4301787137: Input/output
error
and stops after the first pass. I had left the machine unattended, hoping for
all 25 passes to complete.
The -x option does not help. (Therefore probably the 2003-03-08 modification
to shred.c wouldn't have helped either in this case.)
The only option that helps is to use the --size option with a value of the
limit mentioned above (4200966), minus 2, times 1024. Unfortunately this is
a bit complicated, because I don't know where the "minus 2" comes from,
and also because I need 'bc' to compute this, but it is on the root
partition that I just erased through pass 1/25... OK, the offset from the
first error message does it as well...
Suggestion: Could shred, when encountering this error on a block device file,
print the error message but nevertheless continue with the remaining passes?
That would be more useful than the current behaviour.
Bruno
- shred and odd partition sizes,
Bruno Haible <=