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 <[email protected]>:
> 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 <[email protected]>
> 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" <[email protected]>
> >>> To: "users" <[email protected]>
> >>> 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 <[email protected]>
> >>> Sent: Thursday, May 12, 2016 7:07 AM
> >>> To: [email protected]
> >>> 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 <[email protected]>:
> >>>
> >>> 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" <[email protected]>
> >>>>> To: "users" <[email protected]>
> >>>>> 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:[email protected]]
> >>>>> 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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> >>>>> is
> >>>>>
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> >>>>
> >>>>> property of Accelerite, a Persistent Systems business. It is intended
> >>>>>
> >>>> only for
> >>>>
> >>>>> the use of the individual or entity to which it is addressed. If you
> >>>>> are
> >>>>>
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> >>>>
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> >
>
>
> --
>
> Andrija Panić
>
