06-05-2009
Thanks everyone for the responses.
Actually my doubt is if I am doing 2 swipes over the disk with a pattern and its compliment, using either dd/dcfldd for the purpose in a script, then the first swipe should have actually ended up physically on the sectors on disk before the second swipe.
With the script I have pasted in my first post, is the sync in between 2 swipes sufficient to ensure that?
Can anyone help me with some pointers on the impact of OS/disk caches on the way to disk sectors?
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LEARN ABOUT ULTRIX
disktab
disktab(5) File Formats Manual disktab(5)
Name
disktab - disk description file
Syntax
#include <disktab.h>
Description
The file is a simple data base that describes disk geometries and disk partition characteristics. The format is patterned after the termi-
nal data base. Entries in consist of a number of fields separated by colons (:). The first entry for each disk gives the names that are
known for the disk, separated by vertical bars (|). The last name given should be a long name fully identifying the disk.
The following list indicates the normal values stored for each disk entry:
Name Type Description
ns num Number of sectors per track
nt num Number of tracks per cylinder
nc num Total number of cylinders on the disk
ba num Block size for partition `a' (bytes)
bd num Block size for partition `d' (bytes)
be num Block size for partition `e' (bytes)
bf num Block size for partition `f' (bytes)
bg num Block size for partition `g' (bytes)
bh num Block size for partition `h' (bytes)
fa num Fragment size for partition `a' (bytes)
fd num Fragment size for partition `d' (bytes)
fe num Fragment size for partition `e' (bytes)
ff num Fragment size for partition `f' (bytes)
fg num Fragment size for partition `g' (bytes)
fh num Fragment size for partition `h' (bytes)
pa num Size of partition `a' in sectors
pb num Size of partition `b' in sectors
pc num Size of partition `c' in sectors
pd num Size of partition `d' in sectors
pe num Size of partition `e' in sectors
pf num Size of partition `f' in sectors
pg num Size of partition `g' in sectors
ph num Size of partition `h' in sectors
se num Sector size in bytes
ty str Type of disk (e.g. removable, winchester)
The entries can be automatically generated with the program.
Files
See Also
chpt(8), newfs(8)
disktab(5)