Is buffer cache used in 'dd' command?

[Mei Jiao]

Just would like to check that when I run:
# dd if=/dev/rdsk/cXtYdZ of=/dev/null bs=1024

Is buffer cache used here? If yes, is it used upto block size of 1024 only?

Thank you.

[Muthukumar_5]

Hai,

You are not using conv formats in dd command. So it won't use the buffer cache for this. When there is no conv method,the in-core memory is not needed.

Check the dd man page for bs option informations.

Regards,
Muthukumar.

[Con O'Kelly · Accepted solution]

Hi

If you are using raw devices then buffer cache will not be used.

Here is a discussion on dd that may provide further info.
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=190078

Cheers
Con

[Robert-Jan Goossens]

by the way, add the k to the bs=1024

# dd if=/dev/rdsk/cXtYdZ of=/dev/null bs=1024k

it will speed up the process.

Regards,
Robert-Jan