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

[Jhon Masschelein]

Hi,

We do not use qcow images and as I wrote, we're still on 3.2.1 so i 
cannot say if 3.4 makes a difference.

However as you can see, except for the added cd command, the script in 
3.4 still does the exact same thing as its 3.2.1 counterpart so I'm 
doubting this has changed at all?

Now, using qcow images would indeed cause faster deploy times since 
there is no real file copying being done. But then you introduce (I 
think) the issue of "re-assembling" an image when you want to save it, 
download it, back it up, etc...

But again, We're not using 3.4 so if it is solved in there. That is 
great news.
And for those that are still using 3.2(.1) my little fix may still be 
helpful. :)

Wkr,

Jhon


On 04/18/2012 03:31 PM, Shankhadeep Shome wrote:
> Wasn't this addressed in the ON 3.4? You should look into the qcow2
> driver in 3.4. If you think its fast now wait till you try the qcow2
> backing store driver.. :)
>
> On Wed, Apr 18, 2012 at 3:38 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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>
>

-- 
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