On Mon, Feb 22, 2016 at 11:00:53PM +0800, 罗思标 wrote:
> Hi rjones,
>
> Good catch, thanks a lot. Does it only disable from official
> rhel/centos RPM with
> `XXXX-RHEL-7-Reject-use-of-libguestfs-winsupport-features-.patch' in
> libguestfs while it still work in upstream source code (
> e.g. rhel-7.2 branch in https://github.com/libguestfs/libguestfs ) ,

Yes, this patch to disable functionality only applies to RHEL, not to
Fedora and not to upstream.

(It only applies "accidentally" to CentOS, since CentOS compiles the
same RHEL package, including this patch).

> which option need to enable windows VM ntfs and guestmount command
> support when i make configure to compile with the upstream source
> code ?

There's no special ./configure option to enable ntfs-3g in the
upstream code.

What happens is that when the supermin appliance is built (see
https://github.com/libguestfs/libguestfs/tree/master/appliance), if
the ntfs-3g package is installed, then ntfs-3g features are enabled.

> I just work for QEMU and Openstack community and need to modidy the
> VM image(e.g. make initrd for linux and modify windows regedit) to
> improve the success rate of VM image 2V2 from VMware to KVM/Xen
> environment, and find this powerful and amazing tool.
>
> some question still need your confirms:
>
> 1. does libguestfs support to mount the MBR and GPT VM image, is
> there any limitation about it ?

It can handle both partition formats.  See next question.

> 2. how about the VM image has multi partitions and LVM? it's support
> according to my try, but still need your further confirms.

It can handle multiple partitions, and all LVM configuration.

There are some limits on the number of partitions:

 http://libguestfs.org/guestfs.3.html#maximum-number-of-partitions-per-disk

That limit applies to virtio-blk.  It's a good question whether
virtio-scsi (which we now use by default almost everywhere) still has
that limit.  I don't know the answer, but it'll certainly be at least
15 partitions.

> 3. what is the maximum number of guestmount support at the same
> time, does it only restrict by the host Memory and CPU resource ?

If you are using libvirt, then libvirt has a maximum number of
anonymous clients (max_anonymous_clients = 20).  You can raise this by
editing `/etc/libvirt/libvirtd.conf'.

libguestfs has no limits, except host memory/CPU.

FUSE or the fuse.ko kernel module might have its own limits.  I don't
think we have ever found what they are.

During the automated test suite, we test 12 parallel FUSE mounts:

 https://github.com/libguestfs/libguestfs/blob/master/tests/mount-local/test-parallel-mount-local.c#L48

You could try raising that number, but note that you will hit the
libvirt limit (20) unless you either disable libvirt
(LIBGUESTFS_BACKEND=direct) or raise the limit in the libvirtd.conf.

Rich.

--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org