[Lustre-discuss] Lustre with failover configuration

[Atul Vidwansa]

Hi Tharindu,

Some comment inline...

Tharindu Rukshan Bamunuarachchi wrote:
>
> hi all,
>
>  
>
> we used sun cluster for shared storage access. we are going to migrate 
> to lustre.
>
> we have two nodes connected to single 2540 disk array.
>
Sun cluster runs on Solaris whereas Lustre is purely Linux. I hope you 
know that.
>
>  
>
> we are going to keep OSS1/MDS in node A and OSS2/MDS in node B.
>
> Please find attached diagram.
>

It is generally not a good idea to co-locate OSS and MDS on same node. 
It kind of defeats the purpose of using Lustre which separates metadata 
from data. You can still use the shown architecture but I will advise 
MDS being primary on Node A with Node B acting as failover partner. 
Similarly, Node B being primary for OSS with Node A being failover partner.

Also, unlike Sun Cluster, both nodes in Lustre failover pair can not 
talk to same storage simultaneously. They work as a active-passive pair 
of nodes. Please refer to Lustre manual which explains failover in 
detail (manual.lustre.org). Searching Lustre failover in Google shows 
some interesting links with detailed examples. See 
http://mergingbusinessandit.blogspot.com/2008/12/implementing-lustre-failover.html
>
>  
>
> how should I configure lustre to support failover/failout. Ideally 
> single node failure should be transparent to Lustre client.
>
> could you please provide commands to configure MDS/OSS with failover 
> support.
>
See Lustre manual.

>  
>
> should I give same volume for both MDS/OSS ?
>
No. Usually OSS resides on RAID6 volume whereas MDS resides on RAID10 
volume. It can be from same storage box, ST2540 in your case. Lustre 
benefits from having multiple OSS nodes where IO can be striped across OSTs.

Cheers,
-Atul
>
>  
>
> / /
>
> cheers,
>
> __
>
> /tharindu/
>
>  
>
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-- 
==================================
Atul Vidwansa
Sun Microsystems Australia Pty Ltd
Web: http://blogs.sun.com/atulvid
Email: Atul.Vidwansa at Sun.COM