Re: [Libguestfs] virt-sysprep future
On 03/17/2012 07:49 PM, Richard W.M. Jones wrote:
On Sat, Mar 17, 2012 at 06:59:34PM +0800, Wanlong Gao wrote:
> Does RedHat has a plan to support NBD in RHEL in the future?
Not as far as I know.
guestmount is fast enough for me. With inspection:
$ time sh -c 'guestmount -a /dev/vg_pin/F16x64 -i /tmp/mnt; fusermount -u
/tmp/mnt'
real 0m9.999s
user 0m0.081s
sys 0m0.377s
Without inspection:
$ time sh -c 'guestmount -a /dev/vg_pin/F16x64 -m /dev/vg_f16x64/lv_root /tmp/mnt;
fusermount -u /tmp/mnt'
real 0m6.681s
user 0m0.074s
sys 0m0.339s
Currently virt-sysprep runs libguestfs twice (once for inspection,
once to mount). A virt-sysprep that was rewritten not to be a shell
script would only run libguestfs once, so there would be ~10 second
overhead. This overhead is insignificant compared to the downsides of
using nbd: having to run as root, (in)security, not supporting all
guests, creating host device nodes, etc.
[root@Allen ~]# time sh -c 'qemu-nbd -c /dev/nbd0 /dev/sda6; mount /dev/nbd0 ./tmp;
umount ./tmp'
real 0m0.146s
user 0m0.009s
sys 0m0.005s
yes, "having run as root" is one of the shortcomings.
I can't get why nbd causes security problem, do you mean data corruptions in
muti-access?
I can't understand the "not supporting all guest", since libguestfs points
to look into
the guest disk image, the concept of just read the disk images' format head is
better.
Thanks,
Wanlong Gao
Rich.