[Lustre-discuss] MDS doesn't switch to failover OST node

[Brian J. Murrell]

On Wed, 2009-11-18 at 22:54 +0700, Dam Thanh Tung wrote:
> Hi list 

Hi,

> MDS only sent request to the OST which was down and didn't connect to
> our backup (failover) OST, so our backup solution was useless, we lost
> all data from that OST.

I don't think you have actually lost any data.  It's there.  Your
clients (which the MDS is) just don't know to use the failover OSS that
you have set up (but not told Lustre about).

> It's really a disaster for me because we even lost all of our data
> before with the same kind of problem: OST can't connect to MDS !!!!

Failures to connect between nodes does not result in data loss.  The
data is still there.  You just need to have your clients access it.

> Could anyone tell me how to route MDS to connect to our backup OST
> ( with ip address 192.168.1.67 , for example ) ? , to bring our OST
> up ?

It sounds like you need to review the failover section of the manual.

In summary, you need to tell the clients about failover nodes
(--failnode) when you create the filesystem.  You can add this feature
after-the-fact with tunefs.lustre.

b.

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