[Fedora-xen] Guest Image File Size

[Aaron Metzger]

Sadique Puthen wrote:

> 
> Basically it if you don't pre-allocate the entire image, virt-manager 
> creates a sparse file to store the guest data which only occupies disk 
> blocks while you write contents to that sparse file . When checking the 
> size of the pre-allocated and sparse images, you should use "du", not 
> "ls -lh".
> 

Thank you for your insight.  You are correct.

I have a guest image stored in a file called "subversion".

"du" shows the actual size being used is smaller than what "ls" thinks.

du -a subversion
2158768 subversion

ls -ld subversion
-rwxr-xr-x 1 root root 64424509441 2007-11-27 18:16 subversion


I have a follow up question though.  How do you cleanly backup and 
restore these files using the smaller amount of space?  Any simplistic 
program that I try (e.g. "tar") also thinks my file is 60 Gig not 2 Gig 
and creates a real file that uses 60 Gig of actual disk space.

Can anyone share the simple steps with "dd" or other programs that let 
you cleanly store a backup of the guest image which uses the smaller 
amount of space and also correctly restores from that backup in a way 
that preserves the orginal idea of a 60 Gig max guest disk size?

I am sorry if these are just basic Xen or even just basic Unix questions 
that you all already know the answers to as opposed to "fedora-xen" 
questions but I'm sure I'm not the only one who will run into such 
things while trying to virtualize their existing infrastructure using 
Fedora and Xen.  This low traffic list has been a wonderful asset in 
helping with my conversion to Fedora Virtualization.  I appreciate all 
the help I have received.

--
Thanks,
Aaron