[Lustre-discuss] MGS failover

[Brian J. Murrell]

On Wed, 2008-07-30 at 09:48 -0400, Brock Palen wrote:
> The manual does not make much sense when it comes to MGS failover.
> 
> Manual:
> 
> Note – The MGS does not use the --failnode option.

This is true.

> You need to set the
> command on all other nodes of the filesystem (servers and clients),  
> about the
> failover options for the MGS.

This is true also.

> Use the --mgsnode parameter on servers  
> and mount
> address for clients.

Also true.

> The servers need to contact the MGS for  
> configuration
> information;

Also true.

> they cannot query the MGS about the failover partner.

This part is either unclear or wrong.  I guess the question is what the
writer was referring to as "they".  You could file a bug about that.

> This does not make any sense at all, other than you can't use -- 
> failnode

On the MGS, yes.  On servers, yes you can use that option.

> and that clients can't check with two different hosts for  
> MGS data.

They sure can!  That's what the "<mgsspec>:=<mgsnode>[:<mgsnode>]"
syntax in the mount.lustre manpage is all about.

> Our MGS will be on its own LUN setup with heartbeat  
> between two nodes that are also working as an MDS pair.

Good.

> While  
> Heartbeat takes care of mounting the MGS file system, how can we tell  
> clients "if mds1 is down use mds2 for MGS data"

$ man mount.lustre

Check out mgsspec in the OPTIONS section.

b.

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