[gpfsug-discuss] Small cluster

Jonathan Buzzard jonathan at buzzard.me.uk
Thu Mar 3 22:23:08 GMT 2016


On 03/03/16 21:57, Mark.Bush at siriuscom.com wrote:
> I have a client that wants to build small remote sites to sync back to
> an ESS cluster they purchased.  These remote sites are generally
> <15-20TB.  If I build a three node cluster with just internal drives can
> this work if the drives aren’t shared amongst the cluster without FPO or
> GNR(since it’s not ESS)?  Is it better to have a SAN sharing disks with
> the three nodes?  Assuming all are NSD servers (or two at least).  Seems
> like most of the implementations I’m seeing use shared disks so local
> drives only would be an odd architecture right?  What do I give up by
> not having shared disks seen by other NSD servers?
>

Unless you are doing data and metadata replication on the remote sites 
then any one server going down is not good at all. To be honest I have 
only ever seen that sort of setup done once. It was part of a high 
availability web server system. The idea was GPFS provided the shared 
storage between the nodes by replicating everything.

Suffice as to say keeping things polite "don't do that". In reality the 
swear words coming from the admin trying to get GPFS fixed when disks 
failed where a lot more colourful. In the end the system was abandoned 
and migrated to ESX as it was back then. Mind you that was in the days 
of GPFS 2.3 so it *might* be better now; are you feeling lucky?

However a SAS attached Dell MD3 (it's LSI/Netgear Engenio storage so 
basically the same as a DS3000/4000/5000) is frankly so cheap that it's 
just not worth going down that route if you ask me. I would do a two 
server cluster with a tie breaker disk on the MD3 to avoid any split 
brain issues, and use the saving on the third server to buy the MD3 and 
SAS cards.

JAB.

-- 
Jonathan A. Buzzard                 Email: jonathan (at) buzzard.me.uk
Fife, United Kingdom.



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