Re: [Libvir] Re: parted/LVM for ET [Storage manager initial requirements and thoughts
"Richard W.M. Jones" <rjones(a)redhat.com> wrote:
...
From the virt-manager/libvirt p.o.v. it seems to me the important
operations are:
(1) Find attached drives.
(2) Find partitions available & their sizes.
(3) Allocate logical volumes.
(4) Find out how much free space is available on a partition, and
carve out a file.
How about creating a regular partition,
or resizing an existing (non-LVM) file system?
Correct me if I'm wrong (I usually am), but:
Nothing can do (1) except doing a brute force scan over /dev and
looking for likely block devices (this is what vgscan does).
Parted can do (2), with several limitations including sector size. It
can't do (3) at all, but then neither can anything else except forking
the LVM command line tools.
And (4) can be done by libvirtd using ordinary POSIX calls, so no
external library support is needed, just some work to remote those
operations (which is mostly done).
Isn't doing #4 portably pretty tricky? There's still too much
variation, because many of the details aren't covered by POSIX.
At least for GNU df, it was -- it uses the mountlist module from gnulib:
http://www.gnu.org/software/gnulib/MODULES.html
the big pieces:
http://cvs.sv.gnu.org/viewcvs/gnulib/lib/mountlist.c?root=gnulib&view...
http://cvs.sv.gnu.org/viewcvs/gnulib/m4/ls-mntd-fs.m4?root=gnulib&vie...
Of course, if your target is just Linux, then it is easier.