<html><body><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt; color: #000000"><div>Hello michal,<br></div><div><br data-mce-bogus="1"></div><div>Thanks for your answers.<br data-mce-bogus="1"></div><div>If others have same questions, I did found this information below on oVirt web site (http://www.ovirt.org/develop/release-management/features/engine/maximum-memory-size/)</div><div><h2 id="note-on-size-of-maximum-memory" style="box-sizing: border-box; font-family: 'Venturis Sans', 'Venturis Sans Adf', VenturisSans, 'VenturisSans ADF', sans-serif; font-weight: 500; line-height: 1.1; color: #333333; margin-top: 17pt; margin-bottom: 8.5pt; font-size: 25pt; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial;" data-mce-style="box-sizing: border-box; font-family: 'Venturis Sans', 'Venturis Sans Adf', VenturisSans, 'VenturisSans ADF', sans-serif; font-weight: 500; line-height: 1.1; color: #333333; margin-top: 17pt; margin-bottom: 8.5pt; font-size: 25pt; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial;">Note on size of maximum memory</h2><p style="box-sizing: border-box; margin: 0px; color: #333333; font-family: 'Source Sans Pro','Open Sans','Helvetica Neue',Helvetica,Arial,sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial;" data-mce-style="box-sizing: border-box; margin: 0px; color: #333333; font-family: 'Source Sans Pro','Open Sans','Helvetica Neue',Helvetica,Arial,sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial;">If memory hot-plug is not required, max memory can be set to be the same as VM memory. Suggested value is 4x size of VM memory. Larger max memory is discouraged because:</p><ul style="box-sizing: border-box; margin-top: 0px; margin-bottom: 8.5pt; color: #333333; font-family: 'Source Sans Pro', 'Open Sans', 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial;" data-mce-style="box-sizing: border-box; margin-top: 0px; margin-bottom: 8.5pt; color: #333333; font-family: 'Source Sans Pro', 'Open Sans', 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial;"><li style="box-sizing: border-box;" data-mce-style="box-sizing: border-box;">I can make QEMU process to start for longer time.</li><li style="box-sizing: border-box;" data-mce-style="box-sizing: border-box;">If hot plugged memory is also required to be hot unpluggable, it needs to be considered as <em style="box-sizing: border-box;" data-mce-style="box-sizing: border-box;">movable</em> by the guest kernel. Kernel requires the amount of movable memory to be at most 4x larger that non-movable memory for stable run.</li><li style="box-sizing: border-box;" data-mce-style="box-sizing: border-box;">On PowerPC platform continuous block of non-movable memory of size 1/64 of the max memory needs to be allocated for each VM.</li></ul></div><div><br></div><div data-marker="__SIG_PRE__"><div>cordialement, regards,</div><div><br data-mce-bogus="1"></div><table style="margin: 0px; table-layout: fixed; border: none; width: 345pt; padding: 0px;" data-mce-style="margin: 0px; table-layout: fixed; border: none; width: 345pt; padding: 0px;" width="460" cellspacing="0" cellpadding="0" border="0"><tbody><tr><td style="margin: 0; font-size: 11px; font-family: Arial,sans-serif; color: #2b3c7a; line-height: 16px; width: 86.25pt; text-align: left;" data-mce-style="margin: 0; font-size: 11px; font-family: Arial,sans-serif; color: #2b3c7a; line-height: 16px; width: 86.25pt; text-align: left;" width="115" valign="top"><a href="https://www.lyra-network.com/" style="border: none; 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font-size: 12pt;" class=""><div class="">Hello,<br class=""></div><div class=""><br class=""></div><div class="">A new vm setting "maximum memory" has appeared in oVirt >4 which by default has the value "current memory”*4<br class=""></div></div></div></div></blockquote><div><br class=""></div>In 4.1</div><div><br class=""><blockquote class=""><div class=""><div class=""><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt;" class=""><div class=""><br class=""></div><div class="">- Why is "maximum memory" setting necessary to set?</div></div></div></div></blockquote></div><div><blockquote class=""><div class=""><div class=""><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt;" class=""><div class="">- Why isn't this value set to "infinity" by default ?</div></div></div></div></blockquote><div><br class=""></div><div>Because it’s recommended to be about 4x the startup size by linux kernel</div><div class=""><br class=""></div><blockquote class=""><div class=""><div class=""><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt;" class=""><div class=""><br class=""></div><div class="">It seems to me kind of uselessly counter productif to have to decide a maximum memory amount beforehand. if we do this, will we have to set maximum CPU cores also in the future (being devil's advocate here ;) )<br class=""></div></div></div></div></blockquote><div><br class=""></div>You don’t have to decide, you can keep the default 4x.</div><div>For CPUs it is not currently needed and is set according to engine-config maximum supported by qemu-kvm - 288 in 4.1</div><div><br class=""></div><div>Thanks,</div><div>michal</div><div>.<br class=""><blockquote class=""><div class=""><div class=""><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt;" class=""><div class=""><br class=""></div><div class=""><div class="">I did searched oVirt documentation, but very little information is available.</div><div class="">Maybe this is an libvirt question, but I'm hopping a oVirt guru could quickly enlighten me.<br class=""></div></div><div class=""><br class=""></div><div class=""><div class="">cordialement, regards,</div><div class=""><br class=""></div><table style="margin: 0px; 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