Thanks for the responses and the link to pixelbeat. Its very helpful.<br><br>Start with QCOW, even before image is uploaded to Glance, dit help since the image size camedown from 20Gb to 8+Gb. I even set the the force_raw_images=False, and use_cow_images=True in nova.conf and restarted nova services. I still see that the image is copied to _base and then copied again to instances folder. This is probably expected and is the caching feature. But under _base I see two files one with the underscore suffix and one without. Does it mean that each time I launch an instance with a diferent flavour(say disk set to 30Gb), another copy will be created in _base?<br>
<br>root@openstack-kvm1:/var/lib/nova/instances# ls -l _base/ | grep 2b4a8e97317619077645de369a8f9fd63acd1f05<br>-rw-rw-r-- 1 nova nova 8691056640 Mar 5 19:23 2b4a8e97317619077645de369a8f9fd63acd1f05<br>-rw-rw-r-- 1 libvirt-qemu kvm 8691056640 Mar 5 19:23 2b4a8e97317619077645de369a8f9fd63acd1f05_20<br>
root@openstack-kvm1:/var/lib/nova/instances# <br><br>Thanks for all the valuable suggestions. I'll explore the disk merging or separate HDD options as well when possible.<br><br>Regards,<br>Balu<br><br><br><br><br><div class="gmail_quote">
On Tue, Mar 5, 2013 at 6:09 PM, Sylvain Bauza <span dir="ltr"><<a href="mailto:sylvain.bauza@digimind.com" target="_blank">sylvain.bauza@digimind.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>Another option is to merge both Glance
and Nova datadirs on GlusterFS in distributed/replicated array.<br>
That way, all _base images and glance images are on the same
"filesystem" but with distributed I/O.<br>
<br>
-Sylvain<br>
<br>
Le 05/03/2013 13:10, Staicu Gabriel a écrit :<br>
</div>
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<div>Hi,<br>
<br>
As a rule of thumb how I worked <span>around</span> this issue was to add a new hdd. I
allocated this new hdd only to /var/lib/nova/instances/_base
and the other hdd to /var/lib/nova/instances/ so in this
manner to the first time a instance is spawn on server the
process use the full capacity of a hdd.</div>
<div><br>
</div>
<div style="font-style:normal;font-size:16px;background-color:transparent;font-family:times new roman,new york,times,serif">Regards,</div>
<div style="font-style:normal;font-size:16px;background-color:transparent;font-family:times new roman,new york,times,serif">Gabriel<br>
</div>
<div style="font-style:normal;font-size:16px;background-color:transparent;font-family:times new roman,new york,times,serif"><span><br>
</span></div>
<div><br>
</div>
<div style="font-family:times new roman,new york,times,serif;font-size:12pt">
<div style="font-family:times new roman,new york,times,serif;font-size:12pt">
<div dir="ltr"> <font face="Arial">
<hr size="1"> <b><span style="font-weight:bold">From:</span></b>
Pádraig Brady <a href="mailto:P@draigBrady.com" target="_blank"><P@draigBrady.com></a><br>
<b><span style="font-weight:bold">To:</span></b>
Balamurugan V G <a href="mailto:balamuruganvg@gmail.com" target="_blank"><balamuruganvg@gmail.com></a> <br>
<b><span style="font-weight:bold">Cc:</span></b>
<a href="mailto:openstack@lists.launchpad.net" target="_blank">openstack@lists.launchpad.net</a> <br>
<b><span style="font-weight:bold">Sent:</span></b>
Tuesday, March 5, 2013 1:20 PM<br>
<b><span style="font-weight:bold">Subject:</span></b>
Re: [Openstack] [OpenStack] How to speed up the instance
launch time?<br>
</font> </div>
<br>
On 03/05/2013 11:03 AM, Balamurugan V G wrote:<br>
> Hi,<br>
> <br>
> I have a Folsom 2012.2 3 nodes setup like the one
specified at <a href="https://github.com/mseknibilel/OpenStack-Folsom-Install-guide/blob/master/OpenStack_Folsom_Install_Guide_WebVersion.rst" target="_blank">https://github.com/mseknibilel/OpenStack-Folsom-Install-guide/blob/master/OpenStack_Folsom_Install_Guide_WebVersion.rst</a>.
Each node has a 1Tb hard disk with no raid.<br>
> <br>
> Be it the image creation or the Instance creation,
takes a long time(factor of the disk size of the image),
about 15mins for a 20gb image. I can understand the slow
image creation due to the http transfer of the file from a
seperate web server hosting my images to the controller
node. But even the instance creation takes that much or even
a bit longer. I see that the image is copied from the
Controller to Compute node and multiple copies are make in
the compute node. So all this takes long an dis proportional
to the image size. Is there any way to speed up this
process? Is a SAN based backend the only way to go?<br>
<br>
It sounds like you're using raw images throughout?<br>
You might consider using qcow2 images in glance.<br>
Then you can avoid the conversion to raw in the libvirt base<br>
directory by setting force_raw_images=False in nova.conf<br>
That will avoid some of the initial caching penalty.<br>
<br>
Ensuring that you have use_cow_images=True set,<br>
with use CoW images for the instances and improve<br>
instance startup latency.<br>
<br>
Details of the operations and tradeoffs involved are at:<br>
<a href="http://www.pixelbeat.org/docs/openstack_libvirt_images/" target="_blank">http://www.pixelbeat.org/docs/openstack_libvirt_images/</a><br>
<br>
thanks,<br>
Pádraig.<br>
<br>
<br>
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