[Linux-cluster] Remove the clusterness from GFS

[Lin Shen (lshen)]

> -----Original Message-----
> From: linux-cluster-bounces at redhat.com 
> [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Lon Hohberger
> Sent: Monday, January 08, 2007 10:50 AM
> To: linux clustering
> Subject: Re: [Linux-cluster] Remove the clusterness from GFS
> 
> On Mon, 2007-01-08 at 10:39 -0800, Lin Shen (lshen) wrote:
> > How easy is it to
> > remove some or all of the clusterness from GFS such as 
> fencing, cman 
> > and ccsd stuff? I understand that things like dlm must stay 
> for GFS to work.
> 
> I would think it is very difficult.
> 
> You can use GFS on *one* node without a cluster.
> 
> In order to use a clustered file system, you need a cluster.  
> The cluster acts as the control mechanism for accessing the 
> file system.
> Without it, each computer accessing GFS will have no 
> knowledge of when it is safe to write to or read from the 
> file system.  This will lead to file system corruption very quickly.
> 
> If you absolutely can not have a bit of "cluster software 
> running", you'll probably need to use a client/server 
> approach like NFS instead of a cluster file system like GFS.
> 
> 

It's not that we discriminate against cluster software :). We just have 
some worries about the potential impact the cluster suite could bring to
the system. Extra CPU and memory cost is ok, we can consider that's part
of running GFS. The part that gets us wonder is any potential behavioral
changes and instability to the system. After all, the system is
effectively tunrned into a cluster. I read some of the emails in the
alias about cluster issues aside from GFS.   

For instance, we support hot removal/insertion of nodes in the system,
I'm not clear how fencing will get in the way. We're not planning to add
any fencing hardware, and most likely will set fencing mechanism as
manual. Ideally, we'd like to disable fencing except the part that is
needed for running GFS.

lin