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<p class="MsoNormal"><span lang="EN-US">Hello, List.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">We are developing storage systems using 10 NVMes (current test set).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Using MD RAID10 + CLVM/GFS2 over four hosts achieves 22 GB/s (Max. on Reads).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">However, a GFS2 DLM problem occurred. The problem is that each host frequently reports ¡°dlm: gfs2: send_repeat_remove¡± kernel messages, and I/O throughput becomes unstable and low.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I found a GFS2 commit message about ¡°send_repeat_remove¡± function.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">(https://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2.git/commit/?id=96006ea6d4eea73466e90ef353bf34e507724e77)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Information about the test environment.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Four hosts share 10 NVMes, and each host deploys CLVM/GFS2 on top of the cluster MD RAID1 + MD RAID0.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">GFS2 has 2,000 directories, each with 1,900 media files (3 MB on average).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Each host runs 20 threads of NGINX, and each thread randomly reads media files on demand.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">The Linux kernel version is 4.11.8.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Can you offer suggestions or directions to solve these problems?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Thank you in advance :)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">/Jay Sung<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Jay Sung (Baegjae), Manager | Software Defined Storage Lab | SK Telecom Co., LTD.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">bj.sung@sk.com | mobile: +82-10-2087-5637<o:p></o:p></span></p>
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