SUMMARY: making disks equal

From: Gabel Martin <>
Date: Fri Aug 31 2001 - 03:37:54 EDT
Many thanks to:

Paul Hedgepeth		Harrington, David B
Robyn Mills		William Hathaway
eno			Hamid, Amjad
Val Popa		Tim Chipman
Amindra Mahto		Hindley Nick
Paul Keller		McCaffity, Ray
Mike Ekholm		Vipin Sharma
JULIAN, JOHN C.	Dietsch, Nathan
Dave Mitchell		Craig Raskin
Neill, Mark

The best answers:

first using prtvtoc and fmthard duplicate the slice layout to the new disk
2nd figure out the block size for each of the slices using something like
	fstyp -v /dev/rdsk/cXtYdAsB | grep bsize  <-- data block size.
	df -g | grep "block size"
lastly do your dd but give it the block size
p.s. dd is slow you may want to try a different method


----I done it that way--------------------------------

>This seems to take years... another problem is that I don't know if anythig

It will take years - the way you are using the command is very
inefficient.  You should put a block size on the dd commands (use
bs=819200 or something like that) so the disks will be read in large
blocks not character at a time.

>Q: Is the usage of the above mentioned command correct ?

Correct but not efficient - use a block size on the command.

>Q: Can I do it that way?


>Q: (guess) how long will it take (disks are SUN9.0G)

It depends - doing it character by character will take an extremely
long time, if you do the blocking then probably an hour or so.

>Q: Can I monitor the data traffic of the disks or byte exchange ?

You can use iostat to watch the disk utilisation.

>Q: Will the disks be absolutely equal afterwards ?


Brett Lymn, Computer Systems Administrator, BAE SYSTEMS
Received on Fri Aug 31 08:37:54 2001

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