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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Calibri">Well said Marc. I think in IBM’s marketing pitches they make it sound so simple and easy. But this doesn’t take the place of well planned, tested, and properly sized implementations.<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-family:Calibri;color:black">From: </span>
</b><span style="font-family:Calibri;color:black"><gpfsug-discuss-bounces@spectrumscale.org> on behalf of Marc A Kaplan <makaplan@us.ibm.com><br>
<b>Reply-To: </b>gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><br>
<b>Date: </b>Thursday, July 21, 2016 at 8:33 AM<br>
<b>To: </b>gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><br>
<b>Subject: </b>Re: [gpfsug-discuss] NDS in Two Site scenario<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"sans-serif","serif"">I don't know. That said, let's be logical and cautious.
</span><br>
<br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif"">Your network performance has got to be comparable to (preferably better than!) your disk/storage system. </span><br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif"">Think speed, latency, bandwidth, jitter, reliability, security.</span><br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif"">For a production system with data you care about, that probably means a dedicated/private/reserved channel, probably on private or leased fiber.</span><br>
<br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif"">Sure you can cobble together a demo, proof-of-concept, or prototype with less than that, but are you going to bet your career, life, friendships, data on that?</span><br>
<br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif"">Then you have to work through and test failure and recover scenarios...</span><br>
<br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif"">This forum would be one place to gather at least some anecdotes from power users/admins who might be running GPFS clusters spread over</span><br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif"">multiple kilometers... </span><br>
<br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif"">Is there a sale or marketing team selling this? What do they recommend?</span><br>
<br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif"">Here is an excerpt from an IBM white paper I found by googling... Notice the qualifier "high quality wide area network":</span><br>
<br>
"...Synchronous replication works well for many workloads by replicating data across storage arrays within a data center, within a campus or across geographical distances using high quality wide area network connections. When wide area network connections are
not high performance or are not reliable, an asynchronous approach to data replication is required. GPFS 3.5 introduces a feature called Active File Management (AFM).
<span style="font-size:10.0pt;font-family:"sans-serif","serif"">..."<br>
</span><br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif"">Of course GPFS has improved (and been renamed!) since 3.5 but 4.2 cannot magically compensate for a not-so-high-quality network!</span><br>
<br>
<br>
<br>
<br>
<span style="font-size:7.5pt;font-family:"sans-serif","serif";color:#5F5F5F">From: </span><span style="font-size:7.5pt;font-family:"sans-serif","serif"">"Mark.Bush@siriuscom.com" <Mark.Bush@siriuscom.com></span><br>
<span style="font-size:7.5pt;font-family:"sans-serif","serif";color:#5F5F5F">To: </span><span style="font-size:7.5pt;font-family:"sans-serif","serif"">gpfsug main discussion list <gpfsug-discuss@spectrumscale.org></span><br>
<span style="font-size:7.5pt;font-family:"sans-serif","serif";color:#5F5F5F">Date: </span><span style="font-size:7.5pt;font-family:"sans-serif","serif"">07/20/2016 07:34 PM</span><br>
<span style="font-size:7.5pt;font-family:"sans-serif","serif";color:#5F5F5F">Subject: </span><span style="font-size:7.5pt;font-family:"sans-serif","serif"">Re: [gpfsug-discuss] NDS in Two Site scenario</span><br>
<span style="font-size:7.5pt;font-family:"sans-serif","serif";color:#5F5F5F">Sent by: </span><span style="font-size:7.5pt;font-family:"sans-serif","serif"">gpfsug-discuss-bounces@spectrumscale.org</span><o:p></o:p></p>
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<span style="font-size:10.0pt;font-family:Calibri">Marc, what you are saying is anything outside a particular data center shouldn’t be part of a cluster? I’m not sure marketing is in line with this then. </span><br>
<span style="font-size:10.0pt;font-family:Calibri"> </span><br>
<b><span style="font-family:Calibri">From: </span></b><span style="font-family:Calibri"><gpfsug-discuss-bounces@spectrumscale.org> on behalf of Marc A Kaplan <makaplan@us.ibm.com><b><br>
Reply-To: </b>gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><b><br>
Date: </b>Wednesday, July 20, 2016 at 4:52 PM<b><br>
To: </b>gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><b><br>
Subject: </b>Re: [gpfsug-discuss] NDS in Two Site scenario</span><br>
<br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif"">Careful! You need to plan and test, test and plan both failure scenarios and performance under high network loads.<br>
I don't believe GPFS was designed with the idea of splitting clusters over multiple sites. <br>
If your inter-site network runs fast enough, and you can administer it well enough -- perhaps it will work well enough...</span><br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif""><br>
Hint: Think about the what the words "cluster" and "site" mean.</span><br>
<span style="font-size:10.0pt;font-family:"sans-serif","serif""><br>
GPFS does have the AFM feature, which was designed for multi-site deployments.</span><o:p></o:p></p>
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