<html><body><p>Going way off topic... For reasons that are not entirely understood, Spectrum Scale AFM developers who work from India are unable to subscribe to the gpfsug-discuss mailing list. Their mail servers and gpfsug servers don't want to play nice together. So if you want to reach more AFM experts, I recommend going the developerWorks GPFS forum route:<br><br><a href="https://www.ibm.com/developerworks/community/forums/html/forum?id=11111111-0000-0000-0000-000000000479&ps=25">https://www.ibm.com/developerworks/community/forums/html/forum?id=11111111-0000-0000-0000-000000000479&ps=25</a><br><br>yuri<br><br><img width="16" height="16" src="cid:1__=07BBF5F8DF9143218f9e8a93df938690918c07B@" border="0" alt="Inactive hide details for Luke Raimbach ---03/02/2016 08:43:46 AM---Anybody know the answer? > HI All,"><font color="#424282">Luke Raimbach ---03/02/2016 08:43:46 AM---Anybody know the answer? > HI All,</font><br><br><font size="2" color="#5F5F5F">From: </font><font size="2">Luke Raimbach <Luke.Raimbach@crick.ac.uk></font><br><font size="2" color="#5F5F5F">To: </font><font size="2">gpfsug main discussion list <gpfsug-discuss@spectrumscale.org>, "gpfsug main discussion list" <gpfsug-discuss@gpfsug.org>, </font><br><font size="2" color="#5F5F5F">Date: </font><font size="2">03/02/2016 08:43 AM</font><br><font size="2" color="#5F5F5F">Subject: </font><font size="2">Re: [gpfsug-discuss] AFM over NFS vs GPFS</font><br><font size="2" color="#5F5F5F">Sent by: </font><font size="2">gpfsug-discuss-bounces@spectrumscale.org</font><br><hr width="100%" size="2" align="left" noshade style="color:#8091A5; "><br><br><br><tt>Anybody know the answer?<br><br>> HI All,<br>><br>> We have two clusters and are using AFM between them to compartmentalise<br>> performance. We have the opportunity to run AFM over GPFS protocol (over IB<br>> verbs), which I would imagine gives much greater performance than trying to<br>> push it over NFS over Ethernet.<br>><br>> We will have a whole raft of instrument ingest filesets in one storage cluster<br>> which are single-writer caches of the final destination in the analytics cluster.<br>> My slight concern with running this relationship over native GPFS is that if the<br>> analytics cluster goes offline (e.g. for maintenance, etc.), there is an entry in the<br>> manual which says:<br>><br>> "In the case of caches based on native GPFS\u2122 protocol, unavailability of the<br>> home file system on the cache cluster puts the caches into unmounted state.<br>> These caches never enter the disconnected state. For AFM filesets that use GPFS<br>> protocol to connect to the home cluster, if the remote mount becomes<br>> unresponsive due to issues at the home cluster not related to disconnection<br>> (such as a deadlock), operations that require remote mount access such as<br>> revalidation or reading un-cached contents also hang until remote mount<br>> becomes available again. One way to continue accessing all cached contents<br>> without disruption is to temporarily disable all the revalidation intervals until the<br>> home mount is accessible again."<br>><br>> What I'm unsure of is whether this applies to single-writer caches as they<br>> (presumably) never do revalidation. We don't want instrument data capture to<br>> be interrupted on our ingest storage cluster if the analytics cluster goes away.<br>><br>> Is anyone able to clear this up, please?<br>><br>> Cheers,<br>> Luke.<br>><br>> Luke Raimbach\u200b<br>> Senior HPC Data and Storage Systems Engineer, The Francis Crick Institute, Gibbs<br>> Building,<br>> 215 Euston Road,<br>> London NW1 2BE.<br>><br>> E: luke.raimbach@crick.ac.uk<br>> W: </tt><tt>www.crick.ac.uk</tt><tt><br>><br>> The Francis Crick Institute Limited is a registered charity in England and Wales<br>> no. 1140062 and a company registered in England and Wales no. 06885462, with<br>> its registered office at 215 Euston Road, London NW1 2BE.<br>> _______________________________________________<br>> gpfsug-discuss mailing list<br>> gpfsug-discuss at spectrumscale.org<br>> </tt><tt><a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss">http://gpfsug.org/mailman/listinfo/gpfsug-discuss</a></tt><tt><br>The Francis Crick Institute Limited is a registered charity in England and Wales no. 1140062 and a company registered in England and Wales no. 06885462, with its registered office at 215 Euston Road, London NW1 2BE.<br>_______________________________________________<br>gpfsug-discuss mailing list<br>gpfsug-discuss at spectrumscale.org<br></tt><tt><a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss">http://gpfsug.org/mailman/listinfo/gpfsug-discuss</a></tt><tt><br></tt><br><BR>
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