[Dirvish] Full backup every time

Keith Lofstrom keithl at kl-ic.com
Fri Mar 21 21:57:42 UTC 2008


> From: "Jens Lang" <jenslang at yahoo.de>
> To: <dirvish at dirvish.org>
> Sent: Friday, March 21, 2008 4:12 PM
> Subject: [Dirvish] Full backup every time
> 
> > what could be the reason that dirvish make a full backup every time I
> > start the backup? I am running the lates Ubuntu on both, client and 
> > server.

On Fri, Mar 21, 2008 at 05:24:46PM -0400, Kenneth Lerman wrote:
> It is supposed to.

Ken's reply is true, but you might want a little more information
than that.  Dirvish uses rsync to create full and complete images. 
On the server disk, there should be a succession of complete images.
Rsync uses unix/linux hard links to share data file information; if
a file does not change, there may be many links to it, but it is only
stored on the backup disk once.  Thus, a 500GB disk can store what 
appears to be hundreds of 200GB images - only the changed files and
the directory information is added for each successive image.  For
example, I have a 500GB backup disk with about 150 images on it,
each apparently 200GB, and I have used only 350GB of it.  By using
the "branch" feature of dirvish, files that are identical on many
different machines can also share data space.

This is true in the ideal case.  In reality, big files with little
changes ( rotating-name logs, mbox mail folders, vmware images) 
will chew up disk pretty fast.  Use "dateext" for logrotate, 
Maildir format for mail repositories, and samba links to linux
filespace from smaller vmware images to minimize the big file 
changes getting backed up.  Use dirvish-expire to manage storage.
And look on the mailing list archives, the wiki, and the many
FAQs and writeups created by other dirvish users for more hints.

If after doing all these things, dirvish is creating huge images
and not using hardlinks, filling up your backup disk too fast, there
may be other problems.  The helpful people on this list can help
after you have made an effort characterize your problem.

Welcome to dirvish!

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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