Using dd command for wiping disks

[Joanne Joki_1]

We are trying to decommssin our K200. When we enter the following command:

dd if=/dev/zero of=/dev/rdsk/(somedisk) bs=1024

the system goes off and appears to be wiping the disks (the light is on and stays on) but it NEVER returns to prompt. What are we doing wrong?

[harry d brown jr]

here are some hints:

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xa5c60bce6f33d6118fff0090279cd0f9,00.html

I usually use a "count"

live free or die
harry

[T G Manikandan]

Also check this one

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x3c0f36e69499d611abdb0090277a778c,00.html

Thanks

[Pete Randall]

Joanne,

Your block size is only 1024 bytes. That's going to take forever. Try 1024k instead.

Pete

[Cheryl Griffin]

The speed also depends on the size of disk. How large are the disks? Increasing bs as mentioned before will help.

Verify your /dev/zero file has the correct major/minor number. Otherwise nulls may be written instead of zeros.

At 10.20 (minor was 3)
# mknod /dev/zero c 3 0x000003

At 11.00 (minor has to be 4)
# mknod /dev/zero c 3 4 /dev/zero
# ll /dev/zero
crw-rw-rw- 1 bin sys 3 0x000004 Aug 2 2002 /dev/zero

At 11i, insf should create this file automatically, if it doesn't already exist.

Best Wishes,
Cheryl

[Stefan Farrelly]

There was a long discussion about this a while ago. Heres the link.

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x24b53a7b3682d611abdb0090277a778c,00.html

The best way is to not only use /dev/zero but /dev/one, two... etc. There is a perl script on the above link to do random writes of 1's, 2's etc.

[Hai Nguyen_1]

Joanne,

Pete is correct. I myself always use bs=4096k.

Hai

[Sanjay_6]

Hi,

Either increase the block size or stay patient. It takes some time to do the dd, depending on the size of the disk. try,

dd if=/dev/null of=/dev/rdsk/cxtydz bs=1024k

Hope this helps.

Regds

[Joanne Joki_1]

thanks, all. The size of some of the disks are 2gig and some are 4gig. I will try increasing the block size and see if this helps. The minor number was set to three per the instructions I got from HP -- is this going to be a major problem?