[Lustre-discuss] how to define 60 failnodes

[Andreas Dilger]

On 2009-11-09, at 08:31, Brian J. Murrell wrote:
> On Mon, 2009-11-09 at 16:25 +0800, lelustre wrote:
>> So my question is :if I want an OST to failover to any OSS (one of
>> sixty nodes),should I need to defined 60 failnodes when I format the
>> disk?
>
> I'm not really sure that 60 nodes for every OST is really practical
> though.  When an OSS does fail, the process of finding the OST on a
> failover node is serial and linear.  That is, when the OSS providing  
> an
> OST dies, the client cycles through the OST's failover list trying  
> each
> OSS, serially, until it finds the OST.  The time given to each  
> discovery
> attempt is not trivial (i.e. a few seconds or less) so hunting through
> 60 of them will take considerable time.
>
>> or can I use pacemaker to select an oss and modify something to  
>> notify
>> client that the disk is on some OSS？
>
> No.  There is currently no way to push a client towards an OSS for a
> given OST.


That is what the "Imperative Recovery" feature is - having the failover
server notify the client that it has taken over an OST/MDT filesystem,
rather than waiting for the client to time out its RPC and poke around
trying to find which of the failover servers is controlling the OST/MDT.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.