topic Re: Is buffer cache used in 'dd' command? in Operating System - HP-UX

Is buffer cache used in 'dd' command?

Mei Jiao — Thu, 01 Jul 2004 23:43:18 GMT

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.

Re: Is buffer cache used in 'dd' command?

Muthukumar_5 — Thu, 01 Jul 2004 23:54:02 GMT

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.

Re: Is buffer cache used in 'dd' command?

Con O'Kelly — Thu, 01 Jul 2004 23:56:10 GMT

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

Re: Is buffer cache used in 'dd' command?

Robert-Jan Goossens — Fri, 02 Jul 2004 01:12:14 GMT

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