[Lustre-discuss] Start the MGS first?

Nathaniel Rutman Nathan.Rutman at Sun.COM
Fri Mar 27 08:38:53 PDT 2009


Robert LeBlanc wrote:
> For what it's worth, we have multiple Lustre filesystems, so we already have
> our MGS and MDT separate. We also have heartbeat start up the MGS first.
> >From what I recall, the mounts are pretty quick with heartbeat and I'm not
> sure the MGS and MDTs are ready to go when heartbeat starts on the next file
> system. I know the OSTs take some time for timeout.
>   
What would happen with the new process is that the OST and MDT mounts 
would block (probably with an eventual timeout) until the MGS was 
ready.  So as long as you're not serializing mounts in the wrong order, 
this should be fine.

>
> On 3/25/09 1:48 PM, "Nathaniel Rutman" <Nathan.Rutman at Sun.COM> wrote:
>
>   
>> As of Lustre 1.6, servers can be started in any order (after the initial
>> registration at first startup).  Internally, this required significant bending
>> of our connection rules, and with a move toward ZFS becomes even more
>> burdensome.  
>> So my question to the Lustre community is this: would anyone strenuously
>> object to a startup ordering requirement that the MGS must be started before
>> any other servers?
>> This would probably be in the Lustre 3.0 timeframe.  It is also likely that we
>> will have to divorce the MGS and MDT onto separate devices -- no more "combo"
>> MDT/MGSes. 
>>
>>     
>>>>  NR> I think the only reason to have a local config file is to be able to
>>>>  NR> start a server in the absence of the MGS.  How much effort do we want
>>>>  NR> to expend to be able to keep that ability?  I don't think it's a huge
>>>>  NR> burden to say "MGS must be started first".
>>>>         
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>>     
>
>   




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