Bug 459000

Description of problem:

A message came to linux-lvm from somebody who was unsure about how to set up basic LVM in a cluster. Jonathan Brassow suggested that the LVM manual might clarify the following questions:

- Where do I get clvmd?
- How do I set up?
- Do I need to set up an entire cluster if all I want is CLVM?

Looking at the LVM and the Cluster doc, there's no one single place that answers these specific questions simply. The LVM doc might do a better job of cross referencing.

This is the initial email:

> From: Jean Spirat <jeanspirat>
> Date: August 5, 2008 8:36:52 AM CDT
> To: linux-lvm
> Subject: [linux-lvm] the lvm shared storage question of the week
> Reply-To: LVM general discussion and development <linux-lvm>
>
> Hello there,
>
> Is there any hint or any links anyone could share for the use of lvm on an AOE storage (shared block device over the network). I wanted to know how to create lvm group on a device that is shared among several host.
>
>
> so i use debian 4 servers that acces a AOE target drive. The servers all mount the etherdrive and i want to use lvm to partition this 4Terabyte  block device in smaller chunck. what should be the best way to do that ?
>
> While googling about this i found  references to clvm but no documentation i could use on how to set it up. Is this the way to go ?
>
>
> regards,
> Jean.


This is the IRC exchange that between me and Jonathan B.:

<visegrips> "running LVM in a cluster"
* visegrips looks at that
<slevine> visegrips: Setup?  I'm not sure what specifically you mean. Installation?
<slevine> visegrips: Maybe differences between setup in a cluster and setup locally?
<visegrips> slevine, I am a user who has no clue  and just heard about LVM.
<visegrips> slevine, and CLVM
<visegrips> slevine, so I see the admin guide, but I still don't know what steps are
required to setup CLVM
<slevine> slevine: Well, as far as I know there's only the basic manual:
http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.2/html/Cluster_Logical_Volume_Manager/index.html
<slevine> visegrips: Section 1.3, right up front
http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.2/html/Cluster_Logical_Volume_Manager/LVM_Cluster_Overview.html
<visegrips> slevine, (see above)  Yes, I'm looking at the overview now...  I'll look
at the other one next
<slevine> visegrips: Cluster setup and installation in general should be in the cluster
documents. This is the section in the Cluster Administration Overview:
<slevine> http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.2/html/Cluster_Suite_Overview/s1-clvm-overview-CSO.html
<slevine> That is, the section on CLVM
<visegrips> slevine, I'll look at that, thanks.
<slevine> visegrips: And if you conclude that there's something we need that we do not
provide, we can look at adding that...
<visegrips> slevine, an extremely short skim of that page reveals that there is not much
detail there either...
<visegrips> slevine, I see mention of 'clvmd' and that it is important, but not
much about the init script or ... maybe I'm just looking for too much.
<slevine> visegrips: It sounds as if you're looking for procedural setup stuff
<visegrips> slevine, perhaps what we need is a simple reference to the cluster
manual from the LVM manual when CLVM is mentioned
<visegrips> slevine, the user needs to setup a cluster and do LVM operations...  each
manual punts when it comes to talking about the other subject, but perhaps they should
at least mention each other
<slevine> visegrips: Yes, the topics are definitely separated out. Adding a reference
in the text is of course simple.
<visegrips> slevine, If I want CLVM, and all I read in the manual is that
'clvmd' is important - where do I get that, and after I install, why is it complaining?
<visegrips> slevine, ... hmmm, it's complaining about this cluster stuff.  what
is that?  how do I set it up?  do I need to set up everything if all I want is CLVM?
<visegrips> etc.
<visegrips> slevine, I think most of the time we assume (probably correctly)
that users will use a shared FS with CLVM - therefore, they will stumble upon
all the info somehow.
<slevine> visegrips: How does a user know that all they want is CLVM? Because all they
want really is LVM in a cluster.
<visegrips> slevine, this line of discussion comes from a msg sent to linux-lvm today.
<slevine> visegrips: In any case, my note to myself: Beef up section on
running LVM in a cluster. We can get back in touch for more specifics.
<visegrips> k
<slevine> visegrips: Can you capture the message to linux-lvm and send it to me?
It sounds like a useful starting point for me.
<visegrips> slevine, enroute


<visegrips> slevine, well, we know the knowledge he's missing... It was just difficult for me to find documentation that would answer his questions specifically.  (i.e.  Where's the CLVM documenation?  How do I set it up?)  Not really a one-stop shop for that.