Re: Change qcow disk cache=none

Wido den Hollander Wed, 20 Feb 2013 06:54:17 -0800

On 02/20/2013 05:33 AM, Rajesh Battala wrote:

Hi Jason,
If cache=none on the disk then migration of the VM won't work right?.

I did some more reading about this today and it doesn't actually meanthat migration won't work (or can't).

There is a slight chance that when using something like NFS in asyncmode that writes are still in the page cache of the old hypervisor whilethe guest is already on the new hypervisor.

This COULD lead to filesystem corruption inside the VM, but it doesn'thave to be that way.

If you use something like GFS or OCFS2 as a shared filesystem it willwork just fine. Same goes for when you use RBD (which doesn't use thepage cache at all).

I think you are only in "danger" when you are using async NFS or iSCSI,although I'm not completely sure about the latter.


Wido

I was going through RHEL link 
https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/6/html-single/Virtualization_Host_Configuration_and_Guest_Installation_Guide/index.html

Migration restrictions
============================
Because device assignment uses hardware on the specific host where the guest 
was started, migration and save/restore are not supported when device 
assignment is in use. If the guest operating system supports hot-plugging, 
assigned devices can be removed prior to the migration or save/restore 
operation to enable this feature.
Live migration is only possible between hosts with the same CPU type (that is, 
Intel to Intel or AMD to AMD only).
For live migration, both hosts must have the same value set for the No 
eXecution (NX) bit, either on or off.
For migration to work, cache=none must be specified for all block devices 
opened in write mode.
Warning
Failing to include the cache=none option can result in disk corruption.

Enabling this feature will have issues with HA right?

Thanks
Rajesh Battala

-----Original Message-----
From: Rajesh Battala [mailto:rajesh.batt...@citrix.com]
Sent: Tuesday, February 19, 2013 7:43 PM
To: cloudstack-dev@incubator.apache.org
Subject: RE: Change qcow disk cache=none

Great to hear it worked.

From: Jason Villalta [mailto:ja...@rubixnet.com]
Sent: Tuesday, February 19, 2013 7:38 PM
To: cloudstack-dev@incubator.apache.org
Subject: Re: Change qcow disk cache=none

Thanks for all of your help on this guys.  This worked like a charm!
On Mon, Feb 18, 2013 at 5:30 AM, Wido den Hollander
<w...@widodh.nl<mailto:w...@widodh.nl>> wrote:
On 02/18/2013 05:49 AM, Rajesh Battala wrote:
Sounds great.
How are you planning to implement the cache config value.  From GC settings or
as part of offering or a dynamic changeable param to the VM.

This has been covered by this Jira issue:
https://issues.apache.org/jira/browse/CLOUDSTACK-1302

Wido

Thanks
Rajesh Battala

From: Jason Villalta [mailto:ja...@rubixnet.com<mailto:ja...@rubixnet.com>]
Sent: Monday, February 18, 2013 9:51 AM
To: cloudstack-dev@incubator.apache.org<mailto:cloudstack-
d...@incubator.apache.org>
Subject: Re: Change qcow disk cache=none

Yes I have gotten farther.  I have the hard coded parameter changed and the
system Proxy VM is running now but I am running into issues with the secondary
storage vm.  Troubleshooting that now.

As for the cache setting, I think that still need to be setup as a configurable
option without a rebuild.  Once I get the cloud fully functional I will have 
some
time to contribute to this issue.  For now I just need to get this up and 
running.

Thanks,

On Sun, Feb 17, 2013 at 11:11 PM, Rajesh Battala
<rajesh.batt...@citrix.com<mailto:rajesh.batt...@citrix.com><mailto:rajesh.ba
tt...@citrix.com<mailto:rajesh.batt...@citrix.com>>> wrote:
Now you were able to build and run the cloud right.!

Thanks
Rajesh Battala

From: Jason Villalta
[mailto:ja...@rubixnet.com<mailto:ja...@rubixnet.com><mailto:jason@rubix
net.com<mailto:ja...@rubixnet.com>>]
Sent: Monday, February 18, 2013 3:59 AM
To: cloudstack-dev@incubator.apache.org<mailto:cloudstack-
d...@incubator.apache.org><mailto:cloudstack-
d...@incubator.apache.org<mailto:cloudstack-dev@incubator.apache.org>>
Subject: Re: Change qcow disk cache=none Got it, wrong maven version..
On Sun, Feb 17, 2013 at 4:54 PM, Jason Villalta
<ja...@rubixnet.com<mailto:ja...@rubixnet.com><mailto:ja...@rubixnet.co
m<mailto:ja...@rubixnet.com>><mailto:ja...@rubixnet.com<mailto:jason@r
ubixnet.com><mailto:ja...@rubixnet.com<mailto:ja...@rubixnet.com>>>>
wrote:
I tried this method to build 4.0.0 and I get 3 failed dependencies.  Does
something in git need to be updated with different paths?

error: error reading /home/sysadmin/.m2/repository/org/apache/axis2/axis2-
kernel/1.5.1/axis2-kernel-1.5.1.jar; error in opening zip file
error: error reading
/home/sysadmin/.m2/repository/org/apache/axis2/mex/1.5.1/mex-1.5.1-
impl.jar; error in opening zip file
error: error reading /home/sysadmin/.m2/repository/org/apache/axis2/axis2-
mtompolicy/1.5.1/axis2-mtompolicy-1.5.1.jar; error in opening zip file

On Fri, Feb 15, 2013 at 10:16 AM, Marcus Sorensen
<shadow...@gmail.com<mailto:shadow...@gmail.com><mailto:shadowsor@
gmail.com<mailto:shadow...@gmail.com>><mailto:shadow...@gmail.com<m
ailto:shadow...@gmail.com><mailto:shadow...@gmail.com<mailto:shadows
o...@gmail.com>>>> wrote:
If you just want to change 'none' to 'writeback' or something like that:

git clone https://git-wip-us.apache.org/repos/asf/incubator-cloudstack.git
cd incubator-cloudstack
git checkout 4.0
vi
./plugins/hypervisors/kvm/src/com/cloud/hypervisor/kvm/resource/LibvirtVMD
ef.java
# look for the one occurrence of 'none' in this file and change it as you see 
fit

Then build your packages
(https://cwiki.apache.org/CLOUDSTACK/building-with-
maven.html#BuildingwithMaven-BuildingRPMpackages)
mvn install -P deps && ./waf rpm
or
mvn package -P deb

If you want the fully configurable experience from GUI, with per disk-offering
settings, then you'd open the request, and it may make it into 4.2 in May. Or 
you
could pull the git repo and see if the feature applies to 4.1 and build your own
packages in a month or so when the feature branch is ready.
On Fri, Feb 15, 2013 at 7:05 AM, Jason Villalta
<ja...@rubixnet.com<mailto:ja...@rubixnet.com><mailto:ja...@rubixnet.co
m<mailto:ja...@rubixnet.com>><mailto:ja...@rubixnet.com<mailto:jason@r
ubixnet.com><mailto:ja...@rubixnet.com<mailto:ja...@rubixnet.com>>>>
wrote:
So is there anyway to make this work today or will I have to wait until this is
properly implemented?  This may mean I need to take another look at openstack
or opennebula and switch back.

On Fri, Feb 15, 2013 at 9:00 AM, Wido den Hollander
<w...@widodh.nl<mailto:w...@widodh.nl><mailto:w...@widodh.nl<mailto:w
i...@widodh.nl>><mailto:w...@widodh.nl<mailto:w...@widodh.nl><mailto:wi
d...@widodh.nl<mailto:w...@widodh.nl>>>> wrote:
On 02/15/2013 02:31 PM, Jason Villalta wrote:

Is there any way easy way to make this setting dependent on the storage
definition?  For example some primary storage may need this set to one value
such as cache=writeback such as with the case of ZFS, GlusterFS, CEPH.  Then
other storage may want a different setting such as cache=writethough or none
which is the case with a local ext4 storage or NFS.

Exactly.

I brought this up about a week ago, see this thread:
http://markmail.org/thread/qmrod55gfmhwzot4

It shouldn't be a global property, it should be defined per storage pool, or 
even
better, per disk offering.

Right now we are talking about the cache setting, but tomorrow it could be a
different setting.

Wido

On Thu, Feb 14, 2013 at 11:08 PM, Rajesh Battala
<rajesh.batt...@citrix.com<mailto:rajesh.batt...@citrix.com><mailto:rajesh.ba
tt...@citrix.com<mailto:rajesh.batt...@citrix.com>><mailto:rajesh.battala@cit
rix.com<mailto:rajesh.batt...@citrix.com><mailto:rajesh.batt...@citrix.com<
mailto:rajesh.batt...@citrix.com>>>> wrote:

Hi Jason Villalta,
In LibvirtVmDef.java, there is DiskDef class ,  get the cache value from the 
Global
config, while constructing the xml in the override method the class toString()
specify the cache value, currently it is using "none".

NOTE: whenever there is change in GC value, MS should restart for the value to
take effect.

Thanks
Rajesh Battala
-----Original Message-----
From: Rajesh Battala
[mailto:rajesh.batt...@citrix.com<mailto:rajesh.batt...@citrix.com><mailto:raj
esh.batt...@citrix.com<mailto:rajesh.batt...@citrix.com>><mailto:rajesh.batt
a...@citrix.com<mailto:rajesh.batt...@citrix.com><mailto:rajesh.battala@citrix
.com<mailto:rajesh.batt...@citrix.com>>>]
Sent: Friday, February 15, 2013 9:22 AM
To: cloudstack-us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org><mailto:cloudstack-
us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org>><mailto:cloudstack-
us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org><mailto:cloudstack-
us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org>>>; cloudstack-
d...@incubator.apache.org<mailto:d...@incubator.apache.org><mailto:dev@in
cubator.apache.org<mailto:d...@incubator.apache.org>><mailto:dev@incubat
or.apache.org<mailto:d...@incubator.apache.org><mailto:d...@incubator.apac
he.org<mailto:d...@incubator.apache.org>>>
Subject: RE: Change qcow disk cache=none

Hi Jason Villalta,

Can you raise the ticket for the same. I can work on it if you assign to me.

Thanks
Rajesh Battala
-----Original Message-----
From: Edison Su
[mailto:edison...@citrix.com<mailto:edison...@citrix.com><mailto:Edison.su
@citrix.com<mailto:edison...@citrix.com>><mailto:edison...@citrix.com<mail
to:edison...@citrix.com><mailto:edison...@citrix.com<mailto:Edison.su@citri
x.com>>>]
Sent: Friday, February 15, 2013 4:59 AM
To: cloudstack-us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org><mailto:cloudstack-
us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org>><mailto:cloudstack-
us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org><mailto:cloudstack-
us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org>>>
Subject: RE: Change qcow disk cache=none

The code is at https://git-wip-us.apache.org/repos/asf?p=incubator-
cloudstack.git;a=blob;f=plugins/hypervisors/kvm/src/com/cloud/hypervis
or/kv
m/resource/LibvirtVMDef.java;h=acfd9cf1fe8eba217f09e20adf3101d1295d51d

a;hb=HEAD, search "cache".
you can add a global configuration in cloudstack, or add a configuration in
agent.properties, to specify cache attribute.
-----Original Message-----
From: Jason Villalta
[mailto:ja...@rubixnet.com<mailto:ja...@rubixnet.com><mailto:jason@rubix
net.com<mailto:ja...@rubixnet.com>><mailto:ja...@rubixnet.com<mailto:jas
o...@rubixnet.com><mailto:ja...@rubixnet.com<mailto:ja...@rubixnet.com>>

Sent: Thursday, February 14, 2013 2:16 PM
To: cloudstack-us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org><mailto:cloudstack-
us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org>><mailto:cloudstack-
us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org><mailto:cloudstack-
us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org>>>
Subject: Re: Change qcow disk cache=none

Ok, I see the folks at openstack ran into a similar issue.
https://bugs.launchpad.net/nova/+bug/959637

How can I contribute to this?  Can you recommend a part of the code to look at
so I can build and test a patch?

On Thu, Feb 14, 2013 at 5:13 PM, Edison Su
<edison...@citrix.com<mailto:edison...@citrix.com><mailto:Edison.su@citrix.
com<mailto:edison...@citrix.com>><mailto:edison...@citrix.com<mailto:Ediso
n...@citrix.com><mailto:edison...@citrix.com<mailto:edison...@citrix.com>>

wrote:

need to change cloudstack java code, right now, it's hard coded to

"cache=none".

-----Original Message-----
From: Jason Villalta
[mailto:ja...@rubixnet.com<mailto:ja...@rubixnet.com><mailto:jason@rubix
net.com<mailto:ja...@rubixnet.com>><mailto:ja...@rubixnet.com<mailto:jas
o...@rubixnet.com><mailto:ja...@rubixnet.com<mailto:ja...@rubixnet.com>>

Sent: Thursday, February 14, 2013 1:45 PM
To: cloudstack-us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org><mailto:cloudstack-
us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org>><mailto:cloudstack-
us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org><mailto:cloudstack-
us...@incubator.apache.org<mailto:cloudstack-
us...@incubator.apache.org>>>
Subject: Change qcow disk cache=none

Is there a way to change this kvm disk cache setting in Cloudstack or

template?

If so where is the setting applied?

--
--
Jason Villalta
Co-founder
800.799.4407<tel:800.799.4407><tel:800.799.4407<tel:800.799.4407>><tel:800
.799.4407<tel:800.799.4407><tel:800.799.4407<tel:800.799.4407>>> |
www.RubixTechnology.com<http://www.RubixTechnology.com><http://www.
RubixTechnology.com><http://www.RubixTechnology.com>




--
--
Jason Villalta
Co-founder
800.799.4407<tel:800.799.4407><tel:800.799.4407<tel:800.799.4407>><tel:800
.799.4407<tel:800.799.4407><tel:800.799.4407<tel:800.799.4407>>> |
www.RubixTechnology.com<http://www.RubixTechnology.com><http://www.
RubixTechnology.com><http://www.RubixTechnology.com>







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Jason Villalta
Co-founder
800.799.4407<tel:800.799.4407><tel:800.799.4407<tel:800.799.4407>><tel:800
.799.4407<tel:800.799.4407><tel:800.799.4407<tel:800.799.4407>>> |
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RubixTechnology.com><http://www.RubixTechnology.com>



--
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Jason Villalta
Co-founder
[cid:ii_13a3276a82c64fe9]
800.799.4407<tel:800.799.4407><tel:800.799.4407<tel:800.799.4407>> |
www.RubixTechnology.com<http://www.RubixTechnology.com><http://www.
RubixTechnology.com><http://www.rubixtechnology.com/>



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Jason Villalta
Co-founder
[cid:ii_13a3276a82c64fe9]
800.799.4407<tel:800.799.4407><tel:800.799.4407<tel:800.799.4407>> |
www.RubixTechnology.com<http://www.RubixTechnology.com><http://www.
RubixTechnology.com><http://www.rubixtechnology.com/>



--
--
Jason Villalta
Co-founder
[cid:ii_13a3276a82c64fe9]
800.799.4407<tel:800.799.4407> |
www.RubixTechnology.com<http://www.RubixTechnology.com><http://www.r
ubixtechnology.com/>




--
--
Jason Villalta
Co-founder
[cid:ii_13a3276a82c64fe9]
800.799.4407 |
www.RubixTechnology.com<http://www.rubixtechnology.com/>

Re: Change qcow disk cache=none

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