Re: [Fedora-xen] resizing Xen para-virtualized guest partition
On Mon, May 07, 2007 at 08:41:29PM -0400, Paul Wouters wrote:
On Tue, 8 May 2007, John Summerfield wrote:
> btw You can create sparse files in the first place:
> dd if=/dev/zero of=/tmp/ext-fs seek=$((4*1024*1024)) count=0
> mke2fs -F -q /tmp/ext-fs
I understood that using sparse files will significantly slow down
the xenu for the first time, as it keeps growing the fs allocation
underneath it.
That is correct. Never use sparse files if you care about performance
as they exhibit pathelogically bad behaviour while growing the allocation.
Pre-allocation a file should give the best performance for file backed
guests, as close as you'll get to native without using physical devices
directly.
With a little tweaking to the dd command shown above though it ought to
be possible to extend the image, while allocating the data. You basically
want to seek=<current end of file> and then count=<additional space>
desired.
Dan.
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