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From Srikanteswararao Talluri <>
Subject RE: [DOC] Is the Working with Volumes section missing from docs on purpose?
Date Thu, 21 Feb 2013 03:55:30 GMT

Can you share the automated tests you developed for this feature?


-----Original Message-----
From: Marcus Sorensen [] 
Sent: Tuesday, February 19, 2013 23:21
To: Hari Kannan
Cc:; Srikanteswararao Talluri; Jessica Tomechak
Subject: Re: [DOC] Is the Working with Volumes section missing from docs on purpose?

On Mon, Feb 18, 2013 at 1:49 PM, Hari Kannan <> wrote:
> Hi Marcus, devs,
> Can you also please clarify the following:
> - what hypervisor platforms are supported with 4.1?
Per the FS:
   the KVM hypervisor, with focus on qcow2 and CLVM online resize. RBD support is planned.
   Xen supports volume resize with VM shut down
   VMware support was also submitted and applied

> - does this require a reboot of the VM?
   There is no reboot requirement, but it depends on the guest OS.
User should scan the guest's disk controller (this is done differently for each OS and the
admin of that system should be familiar with it) for new disks, and/or reboot.
   Xen requires that the VM be shut down, or the data disk detached, prior the SR reports
that online resize is not supported. The FS states that we'd need someone with more Xen/SR
experience to look into whether that can be fixed.

> - Is this statement from the FS still accurate/implemented? "volume resize will be allowed
between disk offerings with the same storage tag. for example, if an admin has defined a 5GB
and a 10GB disk offering, a user can upgrade from the 5GB to the 10GB. If the admin has made
a custom-sized disk offering available, then resize will work simply by specifying a new,
larger size. Additionally, a data volume can be moved from a static disk offering to a custom
disk offering with the size specified"

Yes. The resize was implemented this way so as not to break the disk offering model. For example,
if an admin only wants to offer 10, 50, and 100G offerings, then allowing resize needs to
stay within those limitations. Thus, unless a disk offering is already a 'custom sized', where
the user can choose a size, we require the user to provide a new offering, and we actually
migrate between offerings, adjusting the size to match.

> - what platforms support downsizing the volume, if any? If downsized, what happens to
the data?
KVM with CLVM, and Xen SR/VHD (customer may not be aware of which xen primary storages use
this on the back end, I think they all do... ??).
I didn't develop the VMware one, but if I recall, shrink wasn't supported.

If downsized, the disk is simply truncated. Therefore, user should resize any partitions/filesystems
prior to shrink, so that any data is moved off of the end of the disk. This is why there's
the extra 'shrinkok' parameter, which protects against inadvertent shrinking of a disk. User
signs off that they know what they're doing. The doc should make it clear that this is a potentially
dangerous operation.

> - It would also be nice to see a short example write up of what needs to be done in the
guest OS to make this work..

The idea was to count on reboot. If admin knows how to rescan disk for changes, and it works,
then bonus!
For linux: echo "- - -" > /sys/class/scsi_host/<host controller of disk>/scan For
Windows, I think you: right-click computer, select 'manage', right-click 'disk management',
select 'rescan disks'
For BSD : ?

> Thanks a lot!
> Hari Kannan
> -----Original Message-----
> From: Radhika Puthiyetath []
> Sent: Monday, February 18, 2013 2:43 AM
> To:; Srikanteswararao Talluri
> Cc: Jessica Tomechak;
> Subject: RE: [DOC] Is the Working with Volumes section missing from docs on purpose?
> Hi Marcus/Talluri
>  I snatched this feature from Jessica :-)
> Could you please explain me the functionality of the Shrink OK button on the Resize Volume
popup ?
> Thanks
> -Radhika
> -----Original Message-----
> From: Marcus Sorensen []
> Sent: Saturday, February 16, 2013 5:46 AM
> To:
> Subject: Re: [DOC] Is the Working with Volumes section missing from docs on purpose?
> That is interesting. Has anyone written the resizing volumes section? I saw a task for
it but nobody assigned.
> On Feb 15, 2013 5:12 PM, "Jessica Tomechak" 
> <>
> wrote:
>> This question on -users prompted me to look for our "Resizing Volumes"
>> section. I discovered that it is missing, along with the entire 
>> "Working with Volumes" section. All the files are in the repo's docs 
>> directory already, so I think it's just an oversight.
>> Before I file a bug and add this info back in, I wonder whether 
>> anyone remembers deciding on purpose to leave this info out? Or has 
>> someone perhaps rewritten this and put it in another part of the docs?
>> The missing section covers:
>> What is a volume
>> Uploading an existing volume to a VM
>> Attaching a volume to a VM
>> Detaching a volume from one VM and attaching it to a different one 
>> Moving volumes from one storage pool to another Resizing volumes 
>> (using VHD) How deleting a volume affects snapshots (it doesn't) How 
>> to configure garbage collection of deleted volumes
>> Jessica T.
>> -----Original Message-----
>> > From: Clayton Weise []
>> > Sent: Friday, February 15, 2013 1:33 PM
>> > To:
>> > Subject: RE: customising the ROOT disk
>> >
>> > Not that I'm recommending or endorsing this method but we have done 
>> > it in the past.  Stop the instance, resize the root volume on your 
>> > hypervisor directly (this process varies based on the hypervisor 
>> > and storage method used), adjust the size to match in the 
>> > CloudStack database (specifically
>> in
>> > the volumes table), and start the instance.
>> >
>> > -----Original Message-----
>> > From: Mathias Mullins []
>> > Sent: Friday, February 15, 2013 12:46 PM
>> > To:
>> > Subject: Re: customising the ROOT disk
>> >
>> > true. you can do that if you have LVM or Volume manager in windows.
>> > But you have to be careful. If that volume gets deleted out from 
>> > under the
>> VM,
>> > your VM is pretty much dead.
>> >
>> > Thank you,
>> > Matt
>> > On Feb 15, 2013, at 3:38 PM, "Thomas Joseph" 
>> > < <>> wrote:
>> >
>> > From  storage tab and create a data disk with the required size, 
>> > assign
>> it
>> > to the VM and then increase the root volume group.
>> >
>> >
>> > Regards,
>> > Thomas
>> >
>> >
>> > -----Original Message-----
>> > From: Nux! []
>> > Sent: 15 February 2013 07:49 PM
>> > To: Cloudstack users
>> > Subject: customising the ROOT disk
>> >
>> > Hi,
>> >
>> > When I'm creating a new instance is there a way to specify the size 
>> > of
>> the
>> > ROOT disk? I see it uses the template's size (which in my case is
>> > tiny) and I need to have it increased.
>> >
>> > Pointers?
>> >
>> > Thanks,
>> >
>> > Lucian
>> >
>> > --
>> > Sent from the Delta quadrant using Borg technology!
>> >
>> > Nux!
>> ><>
>> >
>> >

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