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Re: Documentation: Basic Concepts of OpenStack are lacking from official Getting Started PDF

 

Hi Alexey:


Can you log these issues as separate bugs in the OpenStack Manuals launchpad project <https://launchpad.net/openstack-manuals>? That will make it easier to track and ensure that they get addressed.

Take care,

Lorin
--
Lorin Hochstein
Lead Architect - Cloud Services
Nimbis Services, Inc.
www.nimbisservices.com





On Feb 20, 2012, at 12:16 AM, Alexey Eromenko wrote:

> Hello all,
> 
> Anne: You were recommended contact by Todd Deshane ("deshantm" on IRC)
> about this issue.
> 
> The problem:
> I'm new to OpenStack and while learning it, all of it's concepts seem wild.
> 
> I have read the OpenStack Getting Started Guide PDF (from
> docs.openstack.org), but it doesn't explain the most basic concepts.
> 
> Things like:
> 1. Why Object Storage (swift) vs. Network File System (NFS)
> =============================================
> According to: "notmyname"
> <notmyname> technologov: the things that object storage in general
> (and swift specifically) provides is large scale, cheap, and durable
> storage
> 
> <notmyname> technologov: object storage is all about relaxing some of
> the constraints of a posix-style system. for example, if you don't
> have to provide atomic operations (ie you can rely on eventual
> consistency), you can much more easily scale a storage system and not
> have a central point of failure
> 
> Also:
> I have seen a video, that explains a bit about hashing searches, but
> very incomplete.
> Also what happens if new servers get added or removed ?
> Such concepts need to be added into the docs.
> 
> Does Object Storage also stores files ? (seems yes)
> 
> 2. Nova vs Images (glance) vs. Object Storage (swift)
> =============================================
> 
> Both (1) Nova-volume and (2) glance and (3) swift seem capable of
> storing VM hard disks.
> What's the conceptual difference between the three ?
> 
> Possible Answer:
> "<notmyname> technologov: nova-volume is for block storage attached to
> a VM. glance is to manage the VM images in a nova cluster and provide
> nice ways of storing them (a bridge to the storage, not the storage
> itself). swift is an object storage system that can be used by glance
> or on its own. swift isn't a filesystem, so it's not "mountable" like
> the devices managed with nova-volume"
> 
> Arguments & Discussion:
> <technologov> come on... "mountable" term is a joke... nowadays you
> can mount GMail or Wikipedia... via FUSE
> <technologov> w.p. is not a Filesystem either :)
> 
> <notmyname> ok, so you don't use swift like a traditional hard drive.
> the only access to it is API-based (and the API is http)
> <notmyname> that can be wrapped into a FUSE filesystem (but there are
> big tradeoffs in doing so--advantages too, of course)
> 
> Once we can agree on the concepts, need to patch official docs.
> 
> 3. Minimal OpenStack setup for new developers to get started is ?
> =============================================
> Nova only ? Glance and Swift are optional modules, right?
> 
> I'd be glad to help to improve docs, but I don't understand those
> concepts myself.
> 
> More docs issues:
> =============================================
> 4. Hierarchies & terminology:
> How do you call Live-migration-domain in OpenStack lingo ? (group of
> hosts, where virtual machines can be live-migrated from one to the
> next)
> Are there any other types of domains / virtual machine groups / host
> machine groups in OpenStack concept / terminology ?
> 
> 5. Cross-platform host OS support:
> Currently the heavy use of "iptables" mandates Linux host. This
> assumption is true if you only support KVM, Xen, LXC, OVZ, UML.
> With a possible future port of OpenStack to VirtualBox engine, this
> assumption is false.
> 5.a. Is "iptables" mandatory or optional ?
> 5.b. What other OpenStack features exist that may fail on FreeBSD
> hosts ? And on Windows hosts ?
> 
> NOTE: I'm OK if OpenStack effort stays Linux-only, but this must be
> clearly documented, along with portability hints.
> 
> 6. Also Dashboard GUI was not covered in getting started PDF, which
> seems important.
> 
> 7. Security: Remote VM control is secured ? How ? Libvirtd ?
> (From my quick look it seems that nova connects to remote
> nova-compute, not to libvirtd.)
> 
> 8. Which other important concepts might I miss ?
> 
> -- 
> -Alexey Eromenko "Technologov", 20.02.2012.
> 
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