[svlug] Mass copying

Aaron Lehmann aaronl at vitelus.com
Sat Mar 17 11:51:01 PST 2001


On Sat, Mar 17, 2001 at 11:31:42AM -0800, Rick Moen wrote:
> Summarised at
> http://wwwsc13.custhelp.com/cgi-bin/varesearch/solution?11=010228-0000&130=0983415877&14=&2715=&15=&2716=&57=search&58=&2900=gu7N3VSNLO&25=6&3=rsync
> , among other places.

That's one disgusting URL.

Their instructions seem quite informative. One area where I disagree
is their reccomendation of gzip compression. For example,

   1. rsync: A good, general-purpose recipe is "rsync -avz olddirectory
   newdirectory".
or
   4. "tar": One general-purpose recipe is
   "(cd olddirectory ; 'tar Sczpf - ) | (cd newdirectory ; tar Sxvzpf -"

(BTW, they're missing a ')' on number 4.

As far as I can tell, use of gzip compression when copying between
physical drives translates to:

1. read files
2. compress them
3. decompress them
4. write files

The only advantage of gzip in this sitation that I can think of is the
reduction of data sent through the pipe. I'm unsure of whether a pipe
would slow down the process more than gzipping and ungzipping. Data on
this would be appreciated. Of course, the pipe argument only applies to
#4. #1 still has me stumped.

> > cd /usr
> > cp -a /usr /foo
> 
> Unreliable treatment of sparse files,

Apparently the --sparse flag can fix this.

> and can accidentally copy multiple filesystems, including ones you
> _definitely_ don't want to copy, such as /proc.  To eliminate the
> latter concern, use -x .
 
That's good to hear; I used to do silly things such as
cp -a /boot /bin /etc /sbin ... target to avoid /proc.




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