[one-users] VM clone speed improvement for shared storage clouds

[Jhon Masschelein]

Hi,

Nice simplification.
I did not know about the ssh_exec_and_log function.
Another thing learned. :)

Thank you for including it on the page!

Wkr,

Jhon


On 04/19/2012 11:57 AM, Jaime Melis wrote:
> Hello,
>
> thanks Jhon, this is indeed a very nice tip. It makes perfect sense. We
> are not going to change the current code, because your tip implies that
> the frontend has access to the file-server which needs not be the case.
> However we're going to reflect your suggestion in the documentation.
>
> We have added a simplified version of your guide to the "VM clone speed
> improvement for shared storage clouds" article in
> http://wiki.opennebula.org/#images_and_storage
>
> You're very welcome to modify it!
>
> cheers,
> Jaime
>
> On Wed, Apr 18, 2012 at 9:38 AM, Jhon Masschelein
> <jhon.masschelein at sara.nl <mailto:jhon.masschelein at sara.nl>> wrote:
>
>     Hi,
>
>     In case this has not been mentioned on the list.
>
>     FYI: Below I'm talking about non persistent images since persistent
>     images do not get cloned but symlinked.
>
>     If you have a shared storage cloud, the tm_clone script can easily
>     be improved. before the fix on our cloud, it took about 12 minutes
>     to launch ten virtual machines with 50GB Images.
>
>     After the change, it takes 4 minutes which is quite a nice improvement.
>     (It now takes about 10 minutes to launch 5TB worth of VM images. :) )
>
>     The standard script /usr/lib/one/tm_commands/__shared/tm_clone.sh
>     will execute the following:
>
>     (line 61):
>     ssh_exec_and_log $DST_HOST \
>     "cd $DST_DIR; cp -r $SRC_PATH $DST_PATH" \
>     "Error copying $SRC to $DST"
>
>     (We're running 3,2,1 and the "cd $DST_DIR;" is new in 3.4. Not sure
>     what it is supposed to do but it should not make a difference.)
>
>     The problem with the existing script is that the "cp -r $SRC_PATH
>     $DST_PATH" part is actually reading the whole image from the
>     fileserver to the opennebula server and then writes it back to a
>     different directory on the same fileserver.
>
>     The result is a very busy opennebula server which becomes
>     unresponsive and a under-used (NFS) fileserver.
>
>     When you make sure that the oneadmin user can ssh to the fileserver,
>     and that on the fileserver you put a symbolic link that points
>     /var/lib/one to the exported oneadmin home dir, you can simply
>     change the cp line to
>
>     "ssh $<your_fileserver_here> cp -r $SRC_PATH $DST_PATH"
>
>     This will make oneadmin ssh to the fileserver and do the copy
>     locally on the fileserver.
>
>     This puts the load on the fileserver (where it belongs) and makes
>     the operation very light on the opennebula server which stays
>     responsive.
>
>     Since most shared storage boxes like ours are geared towards fast
>     IO, this gives a very nice deployment speed increase.
>
>     Because the fileserver hostname or ip address needs to be put in the
>     script, it is difficult to make a patch; this info would need to be
>     added to a config file somewhere. I leave that up to a volunteer. :)
>
>     Hoping this is useful to somebody,
>
>     Jhon
>
>     --
>     Jhon Masschelein
>     Senior Systeemprogrammeur
>     SARA - HPCV
>
>     Science Park 140
>     1098 XG Amsterdam
>     T +31 (0)20 592 8099 <tel:%2B31%20%280%2920%20592%208099>
>     F +31 (0)20 668 3167 <tel:%2B31%20%280%2920%20668%203167>
>     M +31 (0)6 4748 9328 <tel:%2B31%20%280%296%204748%209328>
>     E jhon.masschelein at sara.nl <mailto:jhon.masschelein at sara.nl>
>     http://www.sara.nl
>     _________________________________________________
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>
>
>
>
> --
> Jaime Melis
> Project Engineer
> OpenNebula - The Open Source Toolkit for Cloud Computing
> www.OpenNebula.org <http://www.OpenNebula.org> | jmelis at opennebula.org
> <mailto:jmelis at opennebula.org>

-- 
Jhon Masschelein
Senior Systeemprogrammeur
SARA - HPCV

Science Park 140
1098 XG Amsterdam
T +31 (0)20 592 8099
F +31 (0)20 668 3167
M +31 (0)6 4748 9328
E jhon.masschelein at sara.nl
http://www.sara.nl