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From Andrei Mikhailovsky <and...@arhont.com.INVALID>
Subject Re: KVM disk cache option has no effect
Date Thu, 25 Aug 2016 07:42:25 GMT
I've noticed the same behaviour on kvm with ubuntu 14.04 servers on acs 4.7.1.1

Andrei

----- Original Message -----
> From: "Yuriy Karpel" <yuriy@karpel.su>
> To: "users" <users@cloudstack.apache.org>
> Sent: Thursday, 25 August, 2016 07:58:56
> Subject: Re: KVM disk cache option has no effect

> CentOS management and kvm node, Cloudstack 4.7.1, Storage RBD.
> 
> Added value in the table, UI shows that the caching policy WB:
> 
> 151 4 test_cache a6c0b591-0ca7-4938-91f4-8ed961f490b6 test_cache 0 Disk
> (null) 0 0 (null) 0 1 (null) 25.08.2016 6:35:07 0 1 (null) (null) (null)
> (null) (null) (null) (null) Active (null) writeback thin
> 
> 
> 
> Created drive and connected it to the VM, the cache setting is "none":
> 
>    <disk type='network' device='disk'>
>      <driver name='qemu' type='raw' cache='none'/>
>      <auth username='admin'>
>        <secret type='ceph' uuid='f5efdbfb-8fe7-3dfd-bc07-5088222d8b84'/>
>      </auth>
>      <source protocol='rbd'
> name='rbd-cl/59053122-a711-45d5-a801-8b3858d84cdc'>
>        <host name='ceph-mon.test.cloud' port='6789'/>
>      </source>
>      <backingStore/>
>      <target dev='vdb' bus='virtio'/>
>      <serial>59053122a71145d5a801</serial>
>      <alias name='virtio-disk1'/>
>      <address type='pci' domain='0x0000' bus='0x00' slot='0x06'
> function='0x0'/>
>    </disk>
> 
> 
> 
> 
> 
> 2016-08-24 17:27 GMT+03:00 Andrija Panic <andrija.panic@gmail.com>:
> 
>> Hi Enzo,
>>
>> just go to table/view "disk_offering_view" and in the field "cache_mode"
>> insert "writeback" value....
>>
>> Be aware, that if using writeback cache with CEPH - this is not really
>> needed, and perhaps better to use RBD cache on ceph.conf on KVM side...
>> Also note, with writeback cache set - if using NFS as storage - live
>> migrations will not work !
>> With ceph and writeback cache, live migration works (libvirt limitation,
>> you can google it).
>>
>> Best,
>> Andrija
>>
>> On 24 August 2016 at 10:24, (IMIS) Enzo Bettini <enzo.b@imisglobal.com>
>> wrote:
>>
>> > Hi Andrei,
>> >
>> > How did you get around this? Did you manually update the VM configuration
>> > using virsh edit?
>> >
>> > Regards,
>> > Enzo
>> >
>> >
>> > On 15/05/2016 00:31, Andrei Mikhailovsky wrote:
>> >
>> >> Not as far as I know (. The ticket status is closed
>> >>
>> >> Andrei
>> >>
>> >> ----- Original Message -----
>> >>
>> >>> From: "Simon Weller" <sweller@ena.com>
>> >>> To: "users" <users@cloudstack.apache.org>
>> >>> Sent: Thursday, 12 May, 2016 14:38:35
>> >>> Subject: Re: KVM disk cache option has no effect
>> >>> All,
>> >>>
>> >>> Is there a current issue in Jira on this?
>> >>>
>> >>> - Si
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>> ________________________________________
>> >>> From: Yuriy Karpel <yuriy@karpel.su>
>> >>> Sent: Thursday, May 12, 2016 7:07 AM
>> >>> To: users@cloudstack.apache.org
>> >>> Subject: Re: KVM disk cache option has no effect
>> >>>
>> >>> The same function does not work on centos + ceph. CloudStack 4.7.1
>> >>>
>> >>> 2016-05-12 14:29 GMT+03:00 Andrei Mikhailovsky <andrei@arhont.com>:
>> >>>
>> >>> Hi Shweta,
>> >>>>
>> >>>> thanks for your findings. I am very much surprised to see this was
not
>> >>>> discovered earlier, especially since this feature has been implemented
>> >>>> many
>> >>>> versions back (back in version 4.4 or 4.5 i think). I was under
the
>> >>>> impression that people are testing and reporting on the new features
>> >>>> before
>> >>>> they hit the release, which apparently is not the case, at least
for
>> >>>> some
>> >>>> new features. From what I can see this feature was completed about
a
>> >>>> year
>> >>>> ago.
>> >>>>
>> >>>> I've tried to reopen this issue, but i don't have the rights due
to
>> the
>> >>>> Jira being in a temporary Lockdown mode.
>> >>>>
>> >>>> Could someone with the right access reopen this issue on the grounds
>> >>>> that
>> >>>> it was reported (by at least two individuals) that this feature
is not
>> >>>> working.
>> >>>>
>> >>>> Many thanks
>> >>>>
>> >>>> Andrei
>> >>>>
>> >>>> ----- Original Message -----
>> >>>>
>> >>>>> From: "Shweta Agarwal" <shweta.agarwal1@accelerite.com>
>> >>>>> To: "users" <users@cloudstack.apache.org>
>> >>>>> Sent: Thursday, 12 May, 2016 12:02:59
>> >>>>> Subject: RE: KVM disk cache option has no effect
>> >>>>> Hi Andrei,
>> >>>>>
>> >>>>> Few days back I was also doing some testing in this area and
then we
>> >>>>>
>> >>>> found out
>> >>>>
>> >>>>> that cache field in disk offering is just a UI or API parameter.
But
>> in
>> >>>>>
>> >>>> actual
>> >>>>
>> >>>>> implementation of the API we are just neglecting this parameter
. So
>> >>>>> effectively these parameters in disk offering does nothing 
.
>> >>>>>
>> >>>>> Thanks
>> >>>>> Shweta
>> >>>>>
>> >>>>> -----Original Message-----
>> >>>>> From: Andrei Mikhailovsky [mailto:andrei@arhont.com]
>> >>>>> Sent: Thursday, May 12, 2016 4:07 PM
>> >>>>> To: users
>> >>>>> Subject: KVM disk cache option has no effect
>> >>>>>
>> >>>>> Hello
>> >>>>>
>> >>>>> I've been trying to use cache = writeback option for my KVM
>> hypervisor
>> >>>>>
>> >>>> with ceph
>> >>>>
>> >>>>> backend storage. However, when I am launching a vm that uses
the disk
>> >>>>>
>> >>>> offering
>> >>>>
>> >>>>> with cache=writeback, the cache setting is still set to =none
>> according
>> >>>>>
>> >>>> to the
>> >>>>
>> >>>>> ps aux command.The same applies to the root as well as additional
>> data
>> >>>>>
>> >>>> volumes.
>> >>>>
>> >>>>> I am using ACS 4.7.1, both management and hypervisor servers
are
>> Ubuntu
>> >>>>>
>> >>>> 14.04.
>> >>>>
>> >>>>>
>> >>>>> Could someone please advise on how enable writeback cache?
>> >>>>>
>> >>>>> Cheers
>> >>>>>
>> >>>>> Andrei
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>> DISCLAIMER
>> >>>>> ==========
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which
>> >>>>> is
>> >>>>>
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>> >>>>
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If you
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>> >>>>>
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>>
>>
>> --
>>
>> Andrija Panić

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