<div dir="ltr"><div dir="auto"><div>Hi All,<br><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, 9 Nov 2023, 13:19 Robert Hudson, <<a href="mailto:hudrob@gmail.com" target="_blank">hudrob@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">I largely agree with Luke. Given you're on a dedicated iSCSI network, keep it simple. DCB and other services will only add things that you'll later need to troubleshoot and eliminate as the root cause of network issues on your iSCSI network when they invariably happen (it's rare that I've come across a well and consistently configured iSCSI network, and I've been playing in that space since the mid 2000s). Chances are your OS/hypervisor vendor of choice publishes best practices for how to configure DCB - but as noted, DCB is specifically there to deal with converged networks (where your iSCSI traffic is sharing an ethernet fabric with other traffic types), and you don't seem to have that situation.<div><div><br></div><div>Jumbo frames help in busy iSCSI networks by increasing throughput - but you need to make sure every device from one end of the communications to the other fully supports it. Again, follow vendor advice here. Getting this wrong can cause all sorts of "fun".</div></div></div></blockquote></div></div><div dir="auto"><br></div><div dir="auto">Related to MTUs, etc., people here might be interested in a presentation on the topic I did at NZNOG in March.</div><div dir="auto"><br>MTUs, MRUs, PMTUs<br><a href="https://www.youtube.com/live/_D03z8LrauU?si=Mr5hadabWXePhCjk&t=1971">https://www.youtube.com/live/_D03z8LrauU?si=Mr5hadabWXePhCjk&t=1971</a><br><br></div><div dir="auto"><br></div><div dir="auto"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><br></div><div>Flow control, buffer tuning (large buffers tend to help with iSCSI traffic), etc, can all help to eke out a few more small percentage points of performance, but again, the further you drift from the KISS principle, the more fun you're likely to have troubleshooting later.</div></div></blockquote><div><br>Strongly agree with KISS (foreshadowing the advice at the end of the presentation.)<br><br></div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><br></div><div>Above all - set and document policy in all things, audit against that policy both at initial setup and for drift during the lifecycle of the environment.</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, 9 Nov 2023 at 12:20, Luke Iggleden <<a href="mailto:luke@iggleden.com" rel="noreferrer" target="_blank">luke@iggleden.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
<div>
<p>Hi Andres,</p>
<p>Unless you are running other services on the switch it's not
useful.</p>
<p>Typically these are the only useful changes:<br>
</p>
<p>Jumbo Frames (YMMV), depends on vendor.</p>
<p>Flow Control on (so hosts can issue back off - hopefully without
dropping frames)</p>
<p>Depending on the switch, buffer tuning.</p>
<p>Don't use control plane things, like MLAG, Stacking, STP, etc
etc. Flat fabric.</p>
<p><br>
</p>
<p>Cheers,</p>
<p>Luke Iggleden<br>
</p>
<p><br>
</p>
<div>On 9/11/2023 11:14 am, Andres
Miedzowicz wrote:<br>
</div>
<blockquote type="cite">
<div>
<p class="MsoNormal"><span lang="EN-US">Hello everyone,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">I wanted to get some
opinions on the use of DCB and its associated protocols in a
storage-only (iSCSI), non-converged network. Any thoughts
about the pros and cons of enabling DCB in a scenario where
100% of the traffic on a switch is bi-directional iSCSI
storage (virtual machines and backups)?<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">Thanks in advance.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">Andres<u></u><u></u></span></p>
</div>
<br>
<fieldset></fieldset>
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