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From Marcus <>
Subject Re: Change Volume IOPS on fly without detaching the disk feature.
Date Wed, 05 Mar 2014 18:12:16 GMT
Wouldn't this be implemented as just changing disk offerings? The
resizeVolume API call already allows you to switch disk offerings, we
just need to add a hook in there to optionally call the storage driver
(If volume is deployed to a primary storage) to make an update to the
iops properties on the backend storage. Come to think of it, depending
on how storage drivers are implementing the iops/limits feature,
resizeVolume might be breaking this, or simply requiring a reboot to
apply. That is, if the storage driver is setting the iops just once
upon volume creation, it's probably breaking when a user moves a disk
between offerings that may have alternate iops limits (this is
probably not the case for hypervisor throttling, as that's applied
from whatever is current when the VM starts up).

On Wed, Mar 5, 2014 at 9:58 AM, Mike Tutkowski
<> wrote:
> Hi,
> Perhaps I'm not following this correctly, but I'm a bit lost on why we are
> talking about changing settings on running VMs.
> From what I understand, you are a representative of a storage vendor that
> has a rate-limiting feature. You want to be able to not only set the Max
> IOPS, but also adjust them. Is this true?
> If so, I totally agree. SolidFire has control over Min and Max IOPS and it
> is on my to-do list to add support into CloudStack to be able to
> dynamically change these values (right now customers do this from the
> SolidFire API or its GUI).
> If you would like to work on this feature, that would be great. I'd be
> happy to review your design and code.
> One complication is that we are looking at adding support for generic
> key/value pairs for storage plug-ins in 4.5 and this would effectively
> remove the need to have Min and Max IOPS as "special" fields in the
> CloudStack API and GUI.
> I'm going to CC Chris Suichll (from NetApp) as he and I have already
> discussed this generic-properties concept. It would be good to get his
> feedback on how we might go about dynamically updating storage-plug-in
> key/value pairs.
> Thanks!
> Mike
> On Wed, Mar 5, 2014 at 3:12 AM, Wido den Hollander <> wrote:
>> On 03/05/2014 10:12 AM, Wei ZHOU wrote:
>>> I was thinking about it last week.
>>> AFAIK, libvirt-java 0.5.1 does not support change setting on running vms,
>>> but virsh command line and libvirt API supports it.
>>> so the sulution are
>>> (1) change libvirt-java to support it, and make it released in the next
>>> version. Maybe Wido can help us.
>> Sure! That seems the best way forward. What is currently lacking in the
>> libvirt-java bindings?
>>  (2) call virsh command line.
>> Please, please, do not do that. That's very hacky. We should really keep
>> using the libvirt-java bindings and stay away from invoking binaries.
>> Wido
>>  -Wei
>>> 2014-03-05 9:01 GMT+01:00 Punith S <>:
>>>  hi guys,
>>>> we are having a fixed max iops for each volume being attached to the
>>>> instance in managed storage,
>>>> so this a problem where we are making users to pre allocate the iops of
>>>> the
>>>> disk without having an option to change or resize it, similar to the size
>>>> metric.
>>>> so i would like to introduce a new feature which enables to change or
>>>> resize the volume iops on fly without detaching the datadisk of the VM
>>>> with
>>>> zero downtime where performance of the datadisk can be altered at any
>>>> point
>>>> with the available iops of the primary storage pool, which is similar in
>>>> resizing the volume or datadisk of the vm , where in latter we have to
>>>> detach the datadisk.
>>>> what do you guys think about this feature ? any feedback ?
>>>> thanks,
>>>> --
>>>> regards,
>>>> punith s
> --
> *Mike Tutkowski*
> *Senior CloudStack Developer, SolidFire Inc.*
> e:
> o: 303.746.7302
> Advancing the way the world uses the
> cloud<>
> *(tm)*

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