[Xen-users] Re: RE: how to expand a xen image?

[henry ritzlmayr <xen-list@xxxxxx>]

Am Mittwoch, den 03.09.2008, 08:41 +0200 schrieb Heiko:
> On Wed, Sep 3, 2008 at 7:57 AM, henry ritzlmayr <xen-list@xxxxxx> wrote:
> > Am Dienstag, den 02.09.2008, 11:12 -0400 schrieb Dustin Henning:
> >>       I'm not especially familiar with dd, but couldn't it be used for
> >> this?  It seems I recall something about skipping blocks before writing, so
> >> if you skip enough blocks to go to the end of the file and then write 
> >> enough
> >> blocks to extend it as much as you want, wouldn't this make the single disk
> >> that much bigger the next time it is mounted to a domU?  Obviously it would
> >> be wise to back-up the image first, and this would probably be an offline
> >> operation, but it seems to me it might be better (or at least easier to
> >> manage) than having two physical volumes (unless you want to use two real
> >> disks or something).
> >>       Dustin
> >
> > If you like it within one file:
> >
> > dd if=/dev/zero bs=1G count=5 >> imagefile
> >
> > adds five gigs to your imagefile.
> >
> Hello,
> 
> I did it a couple of time the following way:
> 
> shut down the VM,
> 
> dd if=/dev/zero of=/VM/myxen_back_grow.img bs=1M conv=notrunc
> count=5000 seek=10240
> count is the size that you wanna add(here 5GB more)

If you do it that way, be careful on the seek parameter. It has to be at
least bigger than the original file and for performance reasons (sparse
file) it should exactly match the file size.

ThatÂt why I prefer it the way I posted it above which does the same
thing but avoiding both problems.

Henry



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