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    <title>topic Re: Trouble understanding HA Cluster in Availability: HA &amp; FT Discussions</title>
    <link>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185626#M5560</link>
    <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;In older documentations VMware mentioned a minimum of 2GB for ESXi hosts and 3 GB in case they are managed through vCenter Server. I assume this has been removed in the current documentation, because the minimum requirement for ESXi 5.x is 4GB anyway.&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;André&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
    <pubDate>Mon, 11 Aug 2014 12:58:17 GMT</pubDate>
    <dc:creator>a_p_</dc:creator>
    <dc:date>2014-08-11T12:58:17Z</dc:date>
    <item>
      <title>Trouble understanding HA Cluster</title>
      <link>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185617#M5551</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;Hi,&lt;/P&gt;&lt;P&gt;can someone please explain me why my vm in HA cluster is not powering on?&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;I have 2 hosts in HA cluster:&lt;/P&gt;&lt;P&gt;esx1.company.pri&lt;/P&gt;&lt;P&gt;CPU 2x 3395MHz&lt;/P&gt;&lt;P&gt;RAM 4095MB (1287 used for esxi)&lt;/P&gt;&lt;P&gt;esx3.company.pri&lt;/P&gt;&lt;P&gt;CPU 2x 3395MHz&lt;/P&gt;&lt;P&gt;RAM 4095MB (1287 used for esxi)&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;TestCluster is configured as follows:&lt;/P&gt;&lt;P&gt;Host failures the cluster tolerates = 1&lt;/P&gt;&lt;P&gt;Enable: Disallow vm power on operations that violate availability constraints&lt;/P&gt;&lt;P&gt;No DRS&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;I have 3 vm's:&lt;/P&gt;&lt;P&gt;Ubuntu01&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; 1800MB RAM, 1200MB Reservation, no CPU Reservation&lt;/P&gt;&lt;P&gt;Centos7-01&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; 512MB RAM, 300MB Reservation, no CPU Reservation&lt;/P&gt;&lt;P&gt;Centos7-02&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; 512MB RAM, 300MB Reservation, no CPU Reservation&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;I'm using vCenter 5.5 and esxi 5.5&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;Whenever I'm starting Ubuntu01 I'm getting error: "Insufficient resources to satisfy configured failover for vSphere HA".&lt;/P&gt;&lt;P&gt;When I change Ubuntu01 reservation for RAM from 1200MB to 1000MB than I can start Ubuntu01 but after that I can't start Centos7-01. &lt;/P&gt;&lt;P&gt;Can anyone please explain me why this doesn't work?&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Sun, 10 Aug 2014 10:00:17 GMT</pubDate>
      <guid>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185617#M5551</guid>
      <dc:creator>vmSpecDaniel</dc:creator>
      <dc:date>2014-08-10T10:00:17Z</dc:date>
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    <item>
      <title>Re: Trouble understanding HA Cluster</title>
      <link>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185618#M5552</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;With "Host failures the cluster tolerates, HA calculates "Slots" which are used for Admission Control. With a 1800 MB reservation and one failover host you will have only a single slot available for virtual machines, provided there's sufficient free physical memory.&lt;/P&gt;&lt;P&gt;What does the "Advanced Runtime Info" from the HA pane show, and where did you install vCenter Server (as a VM or on a separate host)?&lt;/P&gt;&lt;P&gt;Unless you already saw this, I highly recommend reading &lt;A href="http://www.yellow-bricks.com/vmware-high-availability-deepdiv/" title="http://www.yellow-bricks.com/vmware-high-availability-deepdiv/"&gt;http://www.yellow-bricks.com/vmware-high-availability-deepdiv/&lt;/A&gt;&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;André&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;PS: Discussion moved from &lt;A _jive_internal="true" class="jivecontainerTT-hover-container" data-objectid="4847" data-objecttype="14" href="https://communities.vmware.com/community/vmtn/vsphere/bootcamp/video_8"&gt; 8. Migration Hot &amp;amp; Cold – HA&lt;/A&gt; to &lt;A _jive_internal="true" class="jivecontainerTT-hover-container" data-objectid="3049" data-objecttype="14" href="https://communities.vmware.com/community/vmtn/availability"&gt; Availability: HA &amp;amp; FT&lt;/A&gt;&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Sun, 10 Aug 2014 11:30:36 GMT</pubDate>
      <guid>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185618#M5552</guid>
      <dc:creator>a_p_</dc:creator>
      <dc:date>2014-08-10T11:30:36Z</dc:date>
    </item>
    <item>
      <title>Re: Trouble understanding HA Cluster</title>
      <link>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185619#M5553</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;Hello Daniel,&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;regarding your info its lab environment or production? for test/lab cluster there is no reason for Admission Control to be enabled.&lt;/P&gt;&lt;P&gt;Also be careful with reservations and used them only in extreme cases otherwise they can be counterproductive...&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;Regards,&lt;/P&gt;&lt;P&gt;P.&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Sun, 10 Aug 2014 15:43:41 GMT</pubDate>
      <guid>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185619#M5553</guid>
      <dc:creator>vNEX</dc:creator>
      <dc:date>2014-08-10T15:43:41Z</dc:date>
    </item>
    <item>
      <title>Re: Trouble understanding HA Cluster</title>
      <link>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185620#M5554</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;This is test cluster. I'm turning admission control to test it.&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Mon, 11 Aug 2014 09:32:25 GMT</pubDate>
      <guid>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185620#M5554</guid>
      <dc:creator>vmSpecDaniel</dc:creator>
      <dc:date>2014-08-11T09:32:25Z</dc:date>
    </item>
    <item>
      <title>Re: Trouble understanding HA Cluster</title>
      <link>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185621#M5555</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;vCenter is installed on&lt;SPAN style="color: #666666; font-family: proxima-nova, Arial, sans-serif; font-size: 14px;"&gt; a separate host&lt;/SPAN&gt;.&lt;/P&gt;&lt;P&gt;&lt;SPAN style="color: #666666; font-family: proxima-nova, Arial, sans-serif; font-size: 14px;"&gt;Advanced Runtime Info:&lt;/SPAN&gt;&lt;/P&gt;&lt;P&gt;&lt;span class="lia-inline-image-display-wrapper" image-alt="Capture.JPG"&gt;&lt;img src="https://communities.vmware.com/t5/image/serverpage/image-id/54092i8FB6C7408E96A988/image-size/large?v=v2&amp;amp;px=999" role="button" title="Capture.JPG" alt="Capture.JPG" /&gt;&lt;/span&gt;&lt;/P&gt;&lt;P&gt;I don't understand why there is only one slot per host (2 for cluster). Slot size is 32MHz and 1032MB and each host has 2,5GB free memory so there should be 2 slots per host.&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Mon, 11 Aug 2014 09:38:32 GMT</pubDate>
      <guid>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185621#M5555</guid>
      <dc:creator>vmSpecDaniel</dc:creator>
      <dc:date>2014-08-11T09:38:32Z</dc:date>
    </item>
    <item>
      <title>Re: Trouble understanding HA Cluster</title>
      <link>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185622#M5556</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;A two host HA cluster with the default Admission Control settings, and only 4GB memory is not a real good environment for testing. Anyway, a host in a HA cluster requires a minimum of approximately 2.4GB memory, which may explain why there's only a single 1,032GB slot available per host.&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;André&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Mon, 11 Aug 2014 09:56:20 GMT</pubDate>
      <guid>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185622#M5556</guid>
      <dc:creator>a_p_</dc:creator>
      <dc:date>2014-08-11T09:56:20Z</dc:date>
    </item>
    <item>
      <title>Re: Trouble understanding HA Cluster</title>
      <link>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185623#M5557</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;That's absolutely correct because slot size for memory is dictated by the highest reservation for powered on VM (+ mem overhead).&lt;/P&gt;&lt;P&gt;In your case it is 1000MB (because of Ubuntu01 reservation + 32MB overhead) = 1032MB slot size&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;Next you have to check vmkernel overhead you can verify it via ESXTOP below or through perf charts metrics ("Used by VMkernel " and "Overhead")&lt;/P&gt;&lt;P&gt;&lt;span class="lia-inline-image-display-wrapper" image-alt="Image 18.png"&gt;&lt;img src="https://communities.vmware.com/t5/image/serverpage/image-id/54080iFF08E836FC753945/image-size/large?v=v2&amp;amp;px=999" role="button" title="Image 18.png" alt="Image 18.png" /&gt;&lt;/span&gt; &lt;/P&gt;&lt;P&gt;In your case there is no more resources left for the next slot which is 1032MB no matter if the VM you are trying to power on has only 512MB RAM granted ...&lt;/P&gt;&lt;P&gt;If you want to avoid this hard limit you can override it by HA advanced attribute "das.slotmeminmb" with less value than your maximum VM reservation.&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;&lt;SPAN style="font-size: 8pt;"&gt;_________________________________________________________________________________________&lt;/SPAN&gt;&lt;/P&gt;&lt;P&gt;&lt;SPAN style="font-size: 8pt;"&gt;If you found this or any other answer helpful, please consider to award points. (use Correct or Helpful buttons)&lt;/SPAN&gt;&lt;/P&gt;&lt;P&gt;&lt;SPAN style="font-size: 10pt;"&gt;Regards,&lt;/SPAN&gt;&lt;/P&gt;&lt;P&gt;&lt;SPAN style="font-size: 10pt;"&gt;P.&lt;/SPAN&gt;&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Mon, 11 Aug 2014 12:18:20 GMT</pubDate>
      <guid>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185623#M5557</guid>
      <dc:creator>vNEX</dc:creator>
      <dc:date>2014-08-11T12:18:20Z</dc:date>
    </item>
    <item>
      <title>Re: Trouble understanding HA Cluster</title>
      <link>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185624#M5558</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;This seems to help. I added 2GB to both of my esxi hosts (now 6GB each) and now, when I set &lt;SPAN style="color: #666666; font-family: proxima-nova, Arial, sans-serif; font-size: 14px;"&gt;Ubuntu01 reservation to to 1000MB I have 3 lots on each host.&lt;/SPAN&gt;&lt;/P&gt;&lt;P&gt;a.p. can you post any reference material that would state that &lt;SPAN style="color: #666666; font-family: proxima-nova, Arial, sans-serif; font-size: 14px;"&gt;host in a HA cluster requires a minimum of 2.4GB memory&lt;/SPAN&gt;.&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Mon, 11 Aug 2014 12:19:25 GMT</pubDate>
      <guid>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185624#M5558</guid>
      <dc:creator>vmSpecDaniel</dc:creator>
      <dc:date>2014-08-11T12:19:25Z</dc:date>
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    <item>
      <title>Re: Trouble understanding HA Cluster</title>
      <link>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185625#M5559</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;vNEX,&lt;/P&gt;&lt;P&gt;I went back and set my esxi hosts to 4GB ram each. As you can see vmk memory overhead is 1113MB and memory reservation for &lt;SPAN style="color: #666666; font-family: proxima-nova, Arial, sans-serif; font-size: 14px;"&gt;Ubuntu01 is &lt;/SPAN&gt;&lt;SPAN style="color: #666666; font-family: proxima-nova, Arial, sans-serif; font-size: 14px;"&gt;1032MB. &lt;/SPAN&gt;&lt;/P&gt;&lt;P&gt;&lt;span class="lia-inline-image-display-wrapper" image-alt="Capture.JPG"&gt;&lt;img src="https://communities.vmware.com/t5/image/serverpage/image-id/54093i22A532F127D73600/image-size/large?v=v2&amp;amp;px=999" role="button" title="Capture.JPG" alt="Capture.JPG" /&gt;&lt;/span&gt;&lt;/P&gt;&lt;P&gt;That gives me 2145MB used ram and I have 4096 on host. This should allow me to have two slots per host and I'm getting just one.&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Mon, 11 Aug 2014 12:57:00 GMT</pubDate>
      <guid>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185625#M5559</guid>
      <dc:creator>vmSpecDaniel</dc:creator>
      <dc:date>2014-08-11T12:57:00Z</dc:date>
    </item>
    <item>
      <title>Re: Trouble understanding HA Cluster</title>
      <link>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185626#M5560</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;In older documentations VMware mentioned a minimum of 2GB for ESXi hosts and 3 GB in case they are managed through vCenter Server. I assume this has been removed in the current documentation, because the minimum requirement for ESXi 5.x is 4GB anyway.&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;André&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Mon, 11 Aug 2014 12:58:17 GMT</pubDate>
      <guid>https://communities.vmware.com/t5/Availability-HA-FT-Discussions/Trouble-understanding-HA-Cluster/m-p/2185626#M5560</guid>
      <dc:creator>a_p_</dc:creator>
      <dc:date>2014-08-11T12:58:17Z</dc:date>
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