<html><body><p><font size="2">Hello Giuseppe,</font><br><br><font size="2">Following was my attempt to answer a similar question some months ago. When reading about the different viewpoints of the Zimon sensors, please note that gpfs_fis_bytes_read is a metric provided by the GPFSFileSystemAPI sensor, while gpfs_fs_bytes_read is a metric provided by the GPFSFileSystem sensor. Therefore, gpfs_fis_bytes_read reflects application reads, while gpfs_fs_bytes_read reflects NSD reads.</font><br><br><font size="2">The GPFSFileSystemAPI and GPFSNodeAPI sensor metrics are from the point of view of "applications" in the sense that they provide stats about I/O requests made to files in GPFS file systems from user level applications using POSIX interfaces like open(), close(), read(), write(), etc.</font><br><br><font size="2">This is in contrast to similarly named sensors without the "API" suffix, like GPFSFilesystem and GPFSNode. Those sensors provide stats about I/O requests made by the GPFS code to NSDs (disks) making up GPFS file systems.</font><br><br><font size="2">The relationship between application I/O and disk I/O might or might not be obvious. Consider some examples. An application that starts sequentially reading a file might, at least initially, cause more disk I/O than expected because GPFS has decided to prefetch data. An application write() might not immediately cause the writing of disk blocks, due to the operation of the pagepool. Ultimately, application write()s might cause twice as much data written to disk due to the replication factor of the file system. Application I/O concerns itself with user data; disk I/O might have to occur to handle the user data and associated file system metadata (like inodes and indirect blocks).</font><br><br><font size="2">The difference between GPFSFileSystemAPI and GPFSNodeAPI: GPFSFileSystemAPI reports stats for application I/O per filesystem per node; GPFSNodeAPI reports application I/O stats per node. Similarly, GPFSFilesystem reports stats for disk I/O per filesystem per node; GPFSNode reports disk I/O stats per node.</font><br><font size="2"><br><br>Eric M. Agar<br>agar@us.ibm.com<br><br>IBM Spectrum Scale Level 2<br>Software Defined Infrastructure, IBM Systems<br><br></font><br><br><img width="16" height="16" src="cid:1__=0ABB082DDFC144808f9e8a93df938690918c0AB@" border="0" alt="Inactive hide details for Kristy Kallback-Rose ---07/02/2018 10:06:08 AM---+1 Would love to see more detailed descriptions on Z"><font size="2" color="#424282">Kristy Kallback-Rose ---07/02/2018 10:06:08 AM---+1 Would love to see more detailed descriptions on Zimon metrics.</font><br><br><font size="2" color="#5F5F5F">From: </font><font size="2">Kristy Kallback-Rose <kkr@lbl.gov></font><br><font size="2" color="#5F5F5F">To: </font><font size="2">gpfsug main discussion list <gpfsug-discuss@spectrumscale.org></font><br><font size="2" color="#5F5F5F">Date: </font><font size="2">07/02/2018 10:06 AM</font><br><font size="2" color="#5F5F5F">Subject: </font><font size="2">Re: [gpfsug-discuss] Zimon metrics details</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>+1<br><br>Would love to see more detailed descriptions on Zimon metrics.<br><br>Sent from my iPhone<br><br>On Jul 2, 2018, at 6:50 AM, Lo Re Giuseppe <<a href="mailto:lore@cscs.ch"><u><font color="#0000FF">lore@cscs.ch</font></u></a>> wrote:<br>
<ul><ul>Hi everybody, <br><br>I am extracting the Zimon performance data and uploading them to our elasticsearch cluster. <br>Now that I have the mechanism in place it’s time to understand what I am actually uploading ;) <br><br>Maybe this has been already asked.. where can I find a (as much as possible) detailed explaination of the different Zimon metrics? <br>The SS probelm determination guide doens’t spend more than half a line for each.<br><br>In particular I would like to understand the difference between these ones:<br><br>- gpfs_fs_bytes_read<br>- gpfs_fis_bytes_read<br><br>The second gives tipically higher values than the first one.<br><br>Thanks for any hit.<br><br>Regards,<br><br>Giuseppe<br>
<p><font size="2" face="Tahoma">***********************************************************************</font><p><font size="2" face="Tahoma">Giuseppe Lo Re</font><p><font size="2" face="Tahoma">CSCS - Swiss National Supercomputing Center</font><p><font size="2" face="Tahoma">Via Trevano 131</font><p><font size="2" face="Tahoma">CH-6900 Lugano (TI) Tel: + 41 (0)91 610 8225</font><p><font size="2" face="Tahoma">Switzerland </font><a href="mailto:giuseppe.lore@cscs.ch"><u><font size="2" color="#0000FF" face="Tahoma">Email: giuseppe.lore@cscs.ch</font></u></a><font size="2" face="Tahoma"> </font><p><font size="2" face="Tahoma">***********************************************************************</font><p><br>_______________________________________________<br>gpfsug-discuss mailing list<br>gpfsug-discuss at <a href="http://spectrumscale.org"><u><font color="#0000FF">spectrumscale.org</font></u></a><u><font color="#0000FF"><br></font></u><a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss"><u><font color="#0000FF">http://gpfsug.org/mailman/listinfo/gpfsug-discuss</font></u></a><tt><font size="2">_______________________________________________<br>gpfsug-discuss mailing list<br>gpfsug-discuss at spectrumscale.org<br></font></tt><tt><font size="2"><a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss">http://gpfsug.org/mailman/listinfo/gpfsug-discuss</a></font></tt><tt><font size="2"><br></font></tt><br><br></ul></ul><BR>
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