[SunHELP] using dd

[Steve Pribyl]

dd copies byte for byte the whole device even if it is not used.
when I do some thing like this I ususally add bs=409600.  This will make
the reads and writes larger so it goes faster.  You may have to test this
409600 was for an HP K class box.  This can make performace worse if the
block size is too large.

Steve Pribyl
spribyl at enteract.com
http://www.enteract.com/~spribyl
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On Tue, 6 Feb 2001, Edward Chase wrote:

> I'm working on developing a backup script for a Solaris 2.7 box.
> 
> The machine has 2 internal 18GB hard drives.  (c0d10t0 and c0d11t0)
> 
> I am using the dd command for the first time in hopes for a little 
> reduncancy and backup speed.  Here's my thoughts...
> 
> Both drives are partitioned the same.  Right now, I've issued the following 
> command:
> 
>     dd if=/dev/rdsk/c0t10d0s0 of=/dev/rdsk/c0t11d0s0
> 
> I was thinking that this would create a quick snapshot of one filesystem 
> from one drive to the other and then I was going to run ufsdump from the 
> 2nd drive.  It's the / filesystem if that matters.
> 
> I issued that command over an hour ago and it still appears to be 
> running.  The partition is 17GB or so, but only has 1.5GB of data in it.
> 
> Should this be taking this long?  This machine is a 4 CPU - E4500 w/ 1GB of 
> RAM.  Only the basic OS is running at the moment.
> 
> 
> 
> ---------------------------------------------------------------
>   Edward F. Chase III     |   echase at providence.edu
>   Providence College      |   http://www.providence.edu
>   Computer Services       |   http://studentweb.providence.edu
>   Providence, RI  02918   |
> 
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