[Lustre-discuss] MGS Nids

[Gabriele Paciucci]

For a clearification in a two servers configuration:

server1 -> 192.168.2.20 MGS+MDT+OST0
server2 -> 192.168.2.22 OST1
/dev/sdb is a lun shared between server1 and server 2

from server1: mkfs.lustre --mgs --failnode=192.168.2.22 --reformat /dev/sdb1
from server1: mkfs.lustre  --reformat --mdt --mgsnode=192.168.2.20 
--fsname=prova --failover=192.168.2.22 /dev/sdb4
from server1: mkfs.lustre  --reformat --ost --mgsnode=192.168.2.20 
--failover=192.168.2.22 --fsname=prova /dev/sdb2
from server2: mkfs.lustre  --reformat --ost --mgsnode=192.168.2.20 
--failover=192.168.2.20 --fsname=prova /dev/sdb3


from server1: mount -t lustre /dev/sdb1 /lustre/mgs_prova
from server1: mount -t lustre /dev/sdb4 /lustre/mdt_prova
from server1: mount -t lustre /dev/sdb2 /lustre/ost0_prova
from server2: mount -t lustre /dev/sdb3 /lustre/ost1_prova


from client:
modprobe lustre
mount -t lustre 192.168.2.20 at tcp:192.168.2.22 at tcp:/prova /prova

now halt server1 and mount MGS, MDT and OST0 on server2, the client 
should continue the activity without problem



On 05/20/2010 02:55 PM, Kevin Van Maren wrote:
> leen smit wrote:
>    
>> Ok, no VIP's then.. But how does failover work in lustre then?
>> If I setup everything using the real IP and then mount from a client and
>> bring down the active MGS, the client will just sit there until it comes
>> back up again.
>> As in, there is no failover to the second node.  So how does this
>> internal lustre failover mechanism work?
>>
>> I've been going trought the docs, and I must say there is very little on
>> the failover mechanism, apart from mentions that a seperate app should
>> care of that. Thats the reason I'm implementing keepalived..
>>
>>      
> Right: the external service needs to keep the "mount" active/healthy on
> one of the servers.
> Lustre handles reconnecting clients/servers as long as the volume is
> mounted where it expects
> (ie, the mkfs node or the --failover node).
>    
>> At this stage I really am clueless, and can only think of creating a TUN
>> interface, which will have the VIP address (thus, it becomes a real IP,
>> not just a VIP).
>> But I got a feeling that ain't the right approach either...
>> Is there any docs available where a active/passive MGS setup is described?
>> Is it sufficient to define a --failnode=nid,...  at creation time?
>>
>>      
> Yep.  See Johann's email on the MGS, but for the MDTs and OSTs that's
> all you have to do
> (besides listing both MGS NIDs at mkfs time).
>
> For the clients, you specify both MGS NIDs at mount time, so it can
> mount regardless of which
> node has the active MGS.
>
> Kevin
>
>    
>> Any help would be greatly appreciated!
>>
>> Leen
>>
>>
>> On 05/20/2010 01:45 PM, Brian J. Murrell wrote:
>>
>>      
>>> On Thu, 2010-05-20 at 12:46 +0200, leen smit wrote:
>>>
>>>
>>>        
>>>> Keepalive uses a VIP in a active/passive state. In a failover situation
>>>> the VIP gets transferred to the passive one.
>>>>
>>>>
>>>>          
>>> Don't use virtual IPs with Lustre.  Lustre clients know how to deal with
>>> failover nodes that have different IP addresses and using a virtual,
>>> floating IP address will just confuse it.
>>>
>>> b.
>>>
>>>
>>>
>>>        
>> _______________________________________________
>> Lustre-discuss mailing list
>> Lustre-discuss at lists.lustre.org
>> http://lists.lustre.org/mailman/listinfo/lustre-discuss
>>
>>      
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>
>    


-- 
_Gabriele Paciucci_ http://www.linkedin.com/in/paciucci

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