Jim Meyering wrote:
"Daniel P. Berrange" <berrange redhat com> wrote:On Wed, Mar 14, 2007 at 09:17:37AM +0000, Richard W.M. Jones wrote:...I did look at the API for libparted a few months ago (actually from the rather ancient released version on gnu.org) and it didn't look to me like there was any way to express LVM notions through the API, so I guess this will require a lot of new API calls and structures?The other option is to simply call the LVM commands directly from libvirt which is what pretty much every app seems todo when they need to talk to LVM. We already do this in the network driver backend to deal with iptables and it isn't all that evil. If the libparted developers are working on LVM APIs we should encourage them, but its not clear to me that its worth expending our own resources to develop full LVM support in libparted when libvirt will only ever need a tiny number of LVM operations to be invokved.If the set of LVM operations required by libvirt is really so small, then I'd say it's worth investing in doing the right thing, if only to create the tiny API right away. With a real library API, libvirt stand a much better chance of properly diagnosing, and even detecting, partitioning failures. Of course, when everything works well, there's very little difference, but it's when things go wrong that users will thank us. Can you give me (an LVM newbie) an idea of what the few libvirt-required LVM operations are?
Quoting almost directly from the operations manual at my former workplace, the LVM-related operations needed to create a new VM were:
lvcreate -L 3G -n newroot raidvg lvcreate -L 1G -n newswap raidvg dd if=/dev/raidvg/oldroot of=/dev/raidvg/newroot mkswap /dev/raidvg/newswap (That's right - we used to create new machines by dupping old ones). Rich. -- Emerging Technologies, Red Hat http://et.redhat.com/~rjones/ 64 Baker Street, London, W1U 7DF Mobile: +44 7866 314 421 "[Negative numbers] darken the very whole doctrines of the equations and make dark of the things which are in their nature excessively obvious and simple" (Francis Maseres FRS, mathematician, 1759)
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