[openstack-dev] [Nova][Cinder] Questions re progress

Clint Byrum clint at fewbar.com
Wed Mar 18 19:22:05 UTC 2015

Excerpts from Adam Lawson's message of 2015-03-18 11:25:37 -0700:
> The aim is cloud storage that isn't affected by a host failure and major
> players who deploy hyper-scaling clouds architect them to prevent that from
> happening. To me that's cloud 101. Physical machine goes down, data
> disappears, VM's using it fail and folks scratch their head and ask this
> was in the cloud right? That's the indication of a service failure, not a
> feature.

Ceph provides this for cinder installations that use it.

> I'm just a very big proponent of cloud arch that provides a seamless
> abstraction between the service and the hardware. Ceph and DRDB are decent
> enough. But tying data access to a single host by design is a mistake IMHO
> so I'm asking why we do things the way we do and whether that's the way
> it's always going to be.

Why do you say Ceph is "decent". It solves all your issues you're
talking about, and does so on commodity hardware.

> Of course this bumps into the question whether all apps hosted in the cloud
> should be cloud aware or whether the cloud should have some tolerance for
> legacy apps that are not written that way.

Using volumes is more expensive than using specialized scale-out storage,
aka "cloud aware" storage. But finding and migrating to that scale-out
storage takes time and has a cost too, so volumes have their place and
always will.

So, can you be more clear, what is it that you're suggesting isn't
available now?

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