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RE: [Xen-users] Convert CentOS system to Xen image?


  • To: "Igor Chubin" <igor@xxxxxxx>
  • From: "Ross S. W. Walker" <rwalker@xxxxxxxxxxxxx>
  • Date: Wed, 2 Apr 2008 11:17:15 -0400
  • Cc: James Pifer <jep@xxxxxxxxxxxxxxxx>, Xen List <xen-users@xxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Wed, 02 Apr 2008 08:17:49 -0700
  • Importance: normal
  • List-id: Xen user discussion <xen-users.lists.xensource.com>
  • Priority: normal
  • Thread-index: AciU0Sjg/ygrgLyMSxexW5Q/E02uGgAAKfHw
  • Thread-topic: [Xen-users] Convert CentOS system to Xen image?

Igor Chubin wrote:
> ...
> > > > > > For data partitions like /home you can do a dump, sftp, and restore.
> > > > >
> > > > > Also you can use rsync
> > > > > (it should be installed on both hosts).
> > > > 
> > > > rsync will indiscriminately copy-over files that it shouldn't.
> > > 
> > > What do you mean?
> > 
> > Well rsync was really designed to replicate data from
> > one system to another, but this isn't technically
> > replication here as not all configs will be the same.
> > 
> > If it's a data volume like /home, then you might get
> > by with rsync. I have found though that the time to
> > get rsync going efficiently doesn't pay for a one
> > time operation. If this is done over a secure
> > reliable network and not the Internet, you could do
> > a dump | ssh restore type deal, maybe add a gzip
> > step in there to compress over the wire and it's
> > done.
> 
> 
> If I understand you right, 
> you say that
> 
> 
> hostA# dump / | ssh hostB restore
> 
> is more effective than:
> 
> hostA# rsync -a / hostB:/
> 
> Or you've said 
> <
> > by with rsync. I have found though that the time to
> > get rsync going efficiently doesn't pay for a one
> >
> about setup time?
> 
> rsync installation is very quick.
> It's enough to simply install rsync package
> and then you can run it (it uses ssh as transport).

I was unaware that you didn't need to setup an rsync
daemon on the other end and configure security.

Then sure I guess rsync would be quicker, does it
preserve special files, pipes, symlinks and sparse
files properly?

> > I have been playing around with the idea of using
> > something like 'revisor' from Fedora to capture
> > the basic system settings and packages into a
> > kickstart install iso that you can use to install
> > a PV that's identical to the source. Have it do
> > an RPM audit of all config files except a few
> > key ones like fstab, ifcfg etc and such and tar
> > those up and have it extracted in the %post
> > section of the kickstart... It's an interesting
> > idea... Hmmm
> 
> Really interesting idea. Thank you for it.
> 
> 
> I'm looking for the way how I can 
> automagically (without rsyncing, dumping and another big
> data transfers) create clone of a system 
> from standard repositories.
> 
> 
> Your idea is to package configs delta between
> current system (that we want to clone) and fresh system
> installed from repo state.
> 
> 
> Cloned system configs - fresh system configs => delta.rpm
> 
> 
> And after installing delta.rpm into fresh system 
> we will have system that will be equal to cloned.
> 
> Correct?

Well my idea for the configs was more rudimentary, but
your idea of a delta RPM is perfect! What is the tool
used for creating delta RPMs? All one would need is
to create a list of configs that should never be
packaged and create a delta RPM of all the others...

Then once you have the delta RPM you add it to the
list of RPMs included in the revisor spin and voila!

Hmmm, I suppose when it comes to the actual data you could
do a number of things like tar or cpio to a series of
DVD images. Maybe some dvd authoring tool can help automate
this process... You would need some interesting method to
find all the data though as not all data is in easily
identifiable locations like home. An example of this
would be the samba tdb files like passdb.tdb and
secrets.tdb, which are created after install and aren't
included in the catalog.

-Ross

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