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Hi Mark,

You can grow a VDI without invalidating the snapshot chain.
If this is what you observed, that's reassuring.
If not, let us know.

As long as you stick with the official CLI and not using "internal"
commands,
it is fine.

Which SR type are you using?

Thanks,
Germano


> Begin forwarded message:
>
> *From: *Mark Benson <md.benson@gmail.com <mailto:md.benson@gmail.com>>
> *Date: *4 November 2014 17:14:25 GMT
> *To: *<xen-api@lists.xen.org <mailto:xen-api@lists.xen.org>>
> *Subject: **[Xen-API] xe vdi-resize and effects on snapshots*
>
> Hi,
>
> I have been goofing about with 'growing' VDIs to enlarge available
> disk space on XAPI/Xen. I figured I'd probably need this somewhere
> along the lineas a XAPI/Xen admin.
>
> Do Snapshots survive growing of disk sizes and are they still valid?
> Will they completely rollback a VDI to it's original size and state?
> All my testing seems to indicate this is true but can I have a
> definitive answer from someone who knows for sure?
>
> Thanks,
>
> --
>
> Mark Benson
>
> _______________________________________________
> Xen-api mailing list
> Xen-api@lists.xen.org <mailto:Xen-api@lists.xen.org>
> http://lists.xen.org/cgi-bin/mailman/listinfo/xen-api


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On 11/11/2014 17:49, Germano Percossi wrote:
> Hi Mark,
>
> You can grow a VDI without invalidating the snapshot chain.
> If this is what you observed, that's reassuring.
> If not, let us know.

That seemed to be the case, yes. The snapshots were also restoring the
VDI size at the time of snapshot. I assume that's intended to make the
snapshot contents match the disk size?

> As long as you stick with the official CLI and not using "internal"
> commands,it is fine.

I was using Citrix XenCenter as a management GUI, which seems to be
pretty robust (although occasionally short on error messages).

> Which SR type are you using?

At the time I was using a local LVM volume (type=ext). I have switched
to NFS SRs since (to ease pool sharing, mostly).

My query was more that I wanted to know the expected case, not that I'd
had an anomaly. Thanks for clearing that up!

--

Mark Benson

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On 11/11/14 19:03, Mark Benson wrote:
> On 11/11/2014 17:49, Germano Percossi wrote:
>> Hi Mark,
>>
>> You can grow a VDI without invalidating the snapshot chain.
>> If this is what you observed, that's reassuring.
>> If not, let us know.
>
> That seemed to be the case, yes. The snapshots were also restoring the
> VDI size at the time of snapshot. I assume that's intended to make the
> snapshot contents match the disk size?
>

When you grown a VDI, you grow only the involved leaf of the chain (if any).
I do not wanna go into much detail just because I could be wrong in
some respects, but basically only the leaf VHD is resized while
the other VHDs in the chain are untouched. That's why when you
restore them you see the "old" size.

The resized VHD knows which blocks can be read (if not "dirty")
from the chain and which ones exists only because of the size growth.

>> As long as you stick with the official CLI and not using "internal"
>> commands,it is fine.
>
> I was using Citrix XenCenter as a management GUI, which seems to be
> pretty robust (although occasionally short on error messages).
>

OK. XenCenter and xapi CLI are fine.

> My query was more that I wanted to know the expected case, not that I'd
> had an anomaly. Thanks for clearing that up!
>

You're welcome.

Germano

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