{"id":15,"date":"2011-02-15T16:43:06","date_gmt":"2011-02-15T16:43:06","guid":{"rendered":"http:\/\/sccm.haas.se\/?p=15"},"modified":"2017-02-17T10:48:07","modified_gmt":"2017-02-17T10:48:07","slug":"slow-loading-windowspe","status":"publish","type":"post","link":"http:\/\/sccm.haas.se\/?p=15","title":{"rendered":"When the boot image takes forever to load&#8230;"},"content":{"rendered":"<p>This one isn&#8217;t new but I haven&#8217;t encountered this problem until today.<a href=\"http:\/\/sccm.haas.se\/wp-content\/uploads\/snail-copy.jpg\"><img loading=\"lazy\" class=\"alignright size-full wp-image-51\" style=\"margin: 5px;\" title=\"snail copy\" src=\"http:\/\/sccm.haas.se\/wp-content\/uploads\/snail-copy.jpg\" alt=\"\" width=\"100\" height=\"87\" \/><\/a><br \/>\nMy customers WindowsPE boot image took 1 minute and 15 seconds to load. This is when the PXE-server transfers WindowsPE to the RAM-disk via TFTP. In other words, before the OS-Image gets applied. Adjusting the TFTP-packet size might shorten loading times since larger packets needs fewer acknowledgements from the client. In my customers case it was the fix. With a packet size of 8192 the WindowsPE-image transfer took 26 seconds and with a packet size of 16384 the transfer took only 20 seconds. That&#8217;s going from 2mb\/s to 7.5mb\/s on a 100mbit link.<\/p>\n<p>Previous to SCCM 2007 SP2 you had to download a hotfix but that&#8217;s no longer needed. All you need to do is add the following to your registry:<\/p>\n<p>For <span style=\"color: #008000;\">SCCM 2012<\/span> the path is<br \/>\n<strong>HKEY_LOCAL_MACHINE\\Software\\Microsoft\\SMS\\DP<\/strong><br \/>\nAdd\u00a0the DWord-value <strong>RamDiskTFTPBlockSize\u00a0<\/strong>and set the decimal value to 16384.<\/p>\n<p>If your<span style=\"color: #008000;\"> SCCM 2007<\/span> \u00a0installation OS is 64bit the path is:<\/p>\n<p><strong>HKEY_LOCAL_MACHINE\\SOFTWARE\\wow6432node\\Microsoft\\SMS\\PXE<\/strong><\/p>\n<p>For 32 bit OSes and for <span style=\"color: #008000;\">SCCM 2007<\/span> the path is :<\/p>\n<p><strong>HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\SMS\\PXE<\/strong><\/p>\n<p>Here is the official Microsoft KB: <a title=\"KB968718\" href=\"http:\/\/support.microsoft.com\/kb\/968718\/en-us\" target=\"_self\"> KB968718<\/a><\/p>\n<p>Don&#8217;t forget to restart the WDS-service after you change the registry-value.<\/p>\n<p><strong>Update<\/strong>! With SCCM 2012 build 1606 there&#8217;s a new registry option called &#8220;TFTPWindowsSize&#8221; to modify the window size of TFTP packages. (&#8220;The receive window is the number of bytes a sender can transmit without receiving an acknowledgment.&#8221; &#8211; Microsoft).<\/p>\n<p>J\u00f6rgen Nilsson has done an excellent comparison on how the two registry values impact speed during the download of the bootimage. So have a look at his site here:\u00a0<a href=\"http:\/\/ccmexec.com\/2016\/09\/tweaking-pxe-boot-times-in-configuration-manager-1606\/\">http:\/\/ccmexec.com\/2016\/09\/tweaking-pxe-boot-times-in-configuration-manager-1606\/<\/a><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>This one isn&#8217;t new but I haven&#8217;t encountered this problem until today. My customers WindowsPE boot image took 1 minute and 15 seconds to load. This is when the PXE-server transfers WindowsPE to the RAM-disk via TFTP. In other words, before the OS-Image gets applied. Adjusting the TFTP-packet size might shorten loading times since larger<\/p>\n<p class=\"text-right\"><span class=\"screen-reader-text\">Continue Reading&#8230; When the boot image takes forever to load&#8230;<\/span><a class=\"btn btn-secondary continue-reading\" href=\"http:\/\/sccm.haas.se\/?p=15\">Continue Reading&#8230;<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[9],"tags":[5,46,32,4,47,3],"_links":{"self":[{"href":"http:\/\/sccm.haas.se\/index.php?rest_route=\/wp\/v2\/posts\/15"}],"collection":[{"href":"http:\/\/sccm.haas.se\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/sccm.haas.se\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/sccm.haas.se\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/sccm.haas.se\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=15"}],"version-history":[{"count":32,"href":"http:\/\/sccm.haas.se\/index.php?rest_route=\/wp\/v2\/posts\/15\/revisions"}],"predecessor-version":[{"id":836,"href":"http:\/\/sccm.haas.se\/index.php?rest_route=\/wp\/v2\/posts\/15\/revisions\/836"}],"wp:attachment":[{"href":"http:\/\/sccm.haas.se\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=15"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/sccm.haas.se\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=15"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/sccm.haas.se\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=15"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}