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<p class="MsoNormal">The server disks are already SSD. The total max available lease space according to dhcpd-pools is 283,751. I did a restart on one of the pair earlier and the time was about 10 minutes, but activity is low at the moment since fall semester
hasn’t begun. <o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:12.0pt;font-family:"Times New Roman",serif;color:black">Shane Merritt
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman",serif;color:black">Office of Information Technology
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The University of Alabama<br>
smerritt@ua.edu </span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">dhcp-users <dhcp-users-bounces@lists.isc.org> on behalf of Sten Carlsen <stenc@s-carlsen.dk><br>
<b>Date: </b>Thursday, August 4, 2022 at 2:54 PM<br>
<b>To: </b>Users of ISC DHCP <dhcp-users@lists.isc.org><br>
<b>Subject: </b>[EXTERNAL] Re: extremely slow DHCPD startup time<o:p></o:p></span></p>
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<p class="MsoNormal">On 4 Aug 2022, at 21.05, Greg Sloop <<a href="mailto:gregs@sloop.net">gregs@sloop.net</a>> <<a href="mailto:gregs@sloop.net">gregs@sloop.net</a>> wrote:</p>
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<p class="MsoNormal">I'm sure others will have some useful suggestions - but I do know that improving disk I/O can seriously improve performance.</p>
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<p class="MsoNormal">I'm not sure if that will improve restart/start/reload times.</p>
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<p class="MsoNormal">It would be pretty easy to test though, say swapping for an SSD/Nvme.</p>
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<p class="MsoNormal">(Or if you like living dangerously, putting the disk in RAM.)</p>
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<p class="MsoNormal">On Thu, Aug 4, 2022 at 12:02 PM Shane Merritt <<a href="mailto:smerritt@ua.edu">smerritt@ua.edu</a>> wrote:</p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I have a failover pair of DHCP servers running 4.4.2-P1 that handle a DHCP for a very large wireless network (>75k devices active at any time). The leases file on these boxes is
around 200 megabytes. The problem I am having is when I need to make a change and restart, DHCPD takes over 25 minutes to start giving out addresses. I assume this is due to the large lease file. I see that there are tons of leases in the file that are
“binding state free” that in some cases are months old. Are there any suggestions to improve this situation?<o:p></o:p></p>
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<p class="MsoNormal">AFAIK the server will fill its internal tables with every possible lease, most of them empty or marked free. I could be wrong about this.</p>
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<p class="MsoNormal">So the question is how large your net blocks are?</p>
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<p class="MsoNormal">If you e.g. have a /8 address space, that would amount to the server having to populate 2^24 (16 mill) entries in its internal table and do what ever processing etc it does for each entry. This may take time.</p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt"><span style="font-family:"Times New Roman",serif">Shane Merritt
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Times New Roman",serif">Office of Information Technology
<br>
The University of Alabama<br>
</span><a href="mailto:smerritt@ua.edu" target="_blank"><span style="font-family:"Times New Roman",serif">smerritt@ua.edu</span></a><span style="font-family:"Times New Roman",serif">
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