>Actually I would like wipe off the hard disk
>content permanently before send back to
>vendor due to this hard disk had bad sector.
Most disks have internal bad block replacement system, which has a quantity of spare blocks available. When a block goes bad, the disk firmware marks it as such and uses a spare block in its place. The bad block is completely hidden from the OS. If a bad block is visible in the OS level, it usually means that the disk's internal spare blocks are completely used up.
However, with proper tools (disk manufacturer's factory test software) it may be possible to access the data in the blocks that are marked as bad, and possibly recover data from them. So wiping the disk completely is rather difficult.
If the confidentiality/secrecy of your data is worth to you more than the price of a new disk, don't trust wiping. Have the disks physically destroyed in a way you can trust.
For non-classified data, wiping the disks may be an option. See the links given earlier in this thread.
Mediainit is not the best tool for this, since on modern disks it simply asks the disk firmware to perform the formatting and waits until the firmware reports it's done. However, the firmware's behavior is disk-model specific and generally unknown. The formatting function may:
1.) do nothing at all, if the disk is supposed to be formatted only using the manufacturer's special software/hardware.
2.) stop when it detects an error it can't handle (too many bad blocks, for example), leaving the rest of the disk unwiped.
In Windows, what the "format" command actually does to the hard disks is very much like "pvcreate" or "mkfs" on Unix. On floppy disks, the Windows format command works differently.
The difference between HFS and VxFS:
the HFS is the older one. On PA-RISC architecture HP-UX, the /stand partition must be HFS, the rest can be VxFS. VxFS has more features: it allows large files (more than 2 GB) and on-line resizing (if OnlineJFS package is installed). There may be special cases where HFS is more efficient, but my rule is "use VxFS unless you know HFS is specifically needed".
>mknod /dev/vg15/group c 64 0x0f0000
>1) What is mknod stands for?
It's shortened from "make device node", I think.
>2) Why is group c and not others? what is group c stands for?
The /dev/vg15/group is the name of the device node to create. The rest describes what kind of device node it should be.
There are two kinds of device nodes: character devices (c) and block devices (b).
3) Is 64 stands for OS 64 bits?
No, it's called a "major number" for the device. 0x0f0000 is the "minor number".
Basically, in most unix-like operating systems, the kernel handles all the device access internally using device numbers. The device nodes in /dev directory just provide a mapping between human-readable names and machine-internal numbers.
On HP-UX, when creating a new volume group with command-line tools, you must create a directory (usually /dev/vg
) and a "group" device node for the volume group.
The device node must be a character device (type c), it must have major number 64 and a minor number of the form 0xNN0000, where NN is between 00 and kernel value "maxvgs" and unique among all the volume groups in the system.
MK
