[Lustre-discuss] Lustre with failover configuration

[Atul Vidwansa]

More comments inline..

Tharindu Rukshan Bamunuarachchi wrote:
> hi Atul,
>
> few points ...
>
> 1. we have migrated to SuSE11 from Solaris due to various techno/political
> reasons.
> 2. I will keep OSS1/MDS2 & OSS2/MDS1 etc. as you have instructed.
>
> One last thing ...
>
> so,  I can configure lustre in a way that ... 
> when either node_A or node_B is down (e.g. power failure) , clients can
> still access file system without data lost :-) 
>   
Yes you can, Lustre clients will see brief hang till failover is done 
and will resume their operations (assuming that storage need not undergo 
fsck).

Cheers,
-Atul
> thankx a lot for quick response ...
>
> __
> tharindu
>
>
>
>
> Hi Tharindu,
>
> Some comment inline...
>
> Tharindu Rukshan Bamunuarachchi wrote:
>   
>> 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-failove
> r.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