[Dirvish] Copying dirvish vaults (heavily hard linked)

Keith Lofstrom keithl at kl-ic.com
Thu Mar 6 16:21:53 UTC 2008


> Petcher, Daniel wrote:
DP> > My boss just had a good idea: he suggested exporting an NFS share, then
DP> > rsync will think it's working locally and not bother with the SSH tunnel.

On Wed, Mar 05, 2008 at 10:43:38PM -0500, Bernd Haug wrote:
BH> Now, if you want to do a full copy and don't care about bandwidth and 
BH> transfer volume consumption, why use rsync in the first place and don't 
BH> just cp to the NFS share?
BH> 
BH> It'll simply copy when both sides are local; at least that's how I read

DP> > You  can  also  use rsync in local-only mode, where both the source
DP> > and destination don't have a ':' in the name. In this case it behaves
DP> > like an improved copy command.

BH> in the rsync man page.

A reminder - using any file-level tool (like rsync or cp or dump or
tar) to copy a complete Dirvish vault, with tens or hundreds of images
hard-linked together, may take a very long time.  Even though the
final result (preferably using rsync) will be a similar collection
of hard-linked files of the same size (with only the date stamps on
the soft-linked files different), the system at the sending end will
have to walk through every one of the source images.  This can take
many days or even weeks.

It can be easier to just copy the partition as a binary file, then
use some tool to resize it at the target end.  I am learning about
lvm and the Redhat tool resize2fs (which I just used to double the
size of an active partition - scary!), and will try them on a 
dirvish bank soon.

See also the ancient:  http://wiki.dirvish.org/index.cgi?CopyingDisks

Keith

-- 
Keith Lofstrom          keithl at keithl.com         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs


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