Open Stack

2011/9/2 Paul Voccio <openstack at substation9.com>:
> Vish,
> We've talked about this idea in the past and I agree this works for *nix
> hosts, but a base install of Windows 2k8R2 with CloudServers is 10.7GB.

Yikes.

> If we went with a 10gb base disk solution this obviously won't work.
> Even if we went with a 20gb partition it could become a problem as
> users install programs to C: and then try to do system updates that
> expect to have some reasonable disk available on C:. Providing a clean
> install with < 10gb usable doesn't feel like a good customer
> experience.

What we do now is grow the image if it's smaller than size X. If it's
already of size X or larger, we leave it alone.

I guess we should add a check to verify that the image isn't larger than
the disk size granted to the requested flavour so that people can't
abuse this.

> We have some users that wish to format their disk with other
> filesystems for performance reasons or encrypt them for security
> reasons. Both of these are completely valid. However, this poses a
> problem if we were to try to resize these partitions for them. Easy
> solution is don't touch the partitions and let them do it themselves.
> I think this type of solution works well for power users and
> developers. This does pose a problem for less technical users who
> would resize a disk and then wonder why they don't see the extra space
> as expected. This would create extra support costs that not all
> providers are willing to shoulder.

I think this is the difference between "a cloud" and a "VPS with an API"
making its appearance.

I'm all for building something on top of which someone can provide a
VPS, but that's not the core of what Nova is. It's meant to be "a
cloud".  It's a piece of infrastructure on top of which amazing,
scalable technology can be built. If we document "this is how this thing
behaves.  Deal with it" that should be fine. I'd be really sad if we
weren't able to make the best choice because the best choice might
surprise less technical users using it as a VPS and who haven't read the
documentation.

If a deployer of OpenStack thinks this demographic is particularly
appealing, they can extend the images they offer to notify users about
these things or perhaps even take action on their part. E.g.:

 * E-mail the user telling them this is what they need to do
 * Show a pop-up on login telling them there's unpartitioned space.
   "Click here to extend C: to use this space" or "Click here to
   fire up 'Microsoft Genuine Partitioning Tool 2008 XP'".
 * "We've detected you've grown your Cloud Server. C: has been extended
   to use this new space. Have a nice day."

I don't believe this should be a core concern for Nova. Do you think we
can get that separation of concern to work out for everyone?

> To address this, we designed what we felt was a compromise and let the users
> decide what they feel is the best solution. It would be an extension that
> would let users define what kind of disk management they wish to use,
> 'manual' or 'auto'. Manual would be the hands off approach that would tell
> the system to expand the disk, but not touch the partition.
> Auto would expand the disk along with the partition. The caveat with the
> auto expand would be the filesystem would have to be in a format that the
> host understood.

The potential for filesystem bugs that could bring the host down gives
me the heebie jeebies. I really, really don't want to mount people's
filesystems.

-- 
Soren Hansen        | http://linux2go.dk/
Ubuntu Developer    | http://www.ubuntu.com/
OpenStack Developer | http://www.openstack.org/