<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<style>
<!--
@font-face
{font-family:Calibri}
@font-face
{font-family:Palatino-Roman}
@font-face
{font-family:Palatino-Bold}
@font-face
{font-family:Palatino-Italic}
@font-face
{font-family:XyvisionPiOne}
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif"}
a:link, span.MsoHyperlink
{color:blue;
text-decoration:underline}
a:visited, span.MsoHyperlinkFollowed
{color:purple;
text-decoration:underline}
span.EmailStyle17
{font-family:"Calibri","sans-serif";
color:windowtext}
.MsoChpDefault
{font-family:"Calibri","sans-serif"}
@page WordSection1
{margin:1.0in 1.0in 1.0in 1.0in}
div.WordSection1
{}
-->
</style>
</head>
<body lang="EN-US" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal">Just an FYI to the GPFS user community,</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">We have been testing out GPFS AFM file systems in our required process of file data migration between two GPFS file systems. The two GPFS file systems are managed in two separate GPFS clusters. We have a third GPFS cluster for compute
systems. We created new independent AFM filesets in the new GPFS file system that are linked to directories in the old file system. Unfortunately access to the AFM filesets from the compute cluster completely hang. Access to the other parts of the second
file system is fine. This limitation/issue is not documented in the Advanced Admin Guide.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Further, we performed prefetch operations using a file mmafmctl command, but the process appears to be single threaded and the operation was extremely slow as a result. According to the Advanced Admin Guide, it is not possible to run multiple
prefetch jobs on the same fileset:</p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Palatino-Roman","serif"">GPFS can prefetch the data using the
</span><b><span style="font-size:10.0pt; font-family:"Palatino-Bold","serif"">mmafmctl
</span></b><i><span style="font-size:10.0pt; font-family:"Palatino-Italic","serif"">Device
</span></i><b><span style="font-size:10.0pt; font-family:"Palatino-Bold","serif"">prefetch –j
</span></b><i><span style="font-size:10.0pt; font-family:"Palatino-Italic","serif"">FilesetName
</span></i><span style="font-size:10.0pt; font-family:"Palatino-Roman","serif"">command (which specifies</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Palatino-Roman","serif"">a list of files to prefetch). Note the following about prefetching:</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:XyvisionPiOne">v
</span><span style="font-size:10.0pt; font-family:"Palatino-Roman","serif"">It can be run in parallel on multiple filesets (although more than one prefetching job cannot be run in</span></p>
<p class="MsoNormal"><span style="font-size:10.0pt; font-family:"Palatino-Roman","serif"">parallel on a single fileset).</span></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">We were able to quickly create the “--home-inode-file” from the old file system using the mmapplypolicy command as the documentation describes. However the AFM prefetch operation is so slow that we are better off running parallel rsync
operations between the file systems versus using the GPFS AFM prefetch operation.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Cheers,</p>
<p class="MsoNormal">-Bryan</p>
<p class="MsoNormal"> </p>
</div>
<br>
<hr>
<font face="Arial" color="Gray" size="1"><br>
Note: This email is for the confidential use of the named addressee(s) only and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you are hereby notified that any review, dissemination or copying of this
email is strictly prohibited, and to please notify the sender immediately and destroy this email and any attachments. Email transmission cannot be guaranteed to be secure or error-free. The Company, therefore, does not make any guarantees as to the completeness
or accuracy of this email or any attachments. This email is for informational purposes only and does not constitute a recommendation, offer, request or solicitation of any kind to buy, sell, subscribe, redeem or perform any type of transaction of a financial
product.<br>
</font>
</body>
</html>