{"id":4361,"date":"2016-03-08T13:19:53","date_gmt":"2016-03-08T21:19:53","guid":{"rendered":"http:\/\/www.atumvirt.com\/?p=4361"},"modified":"2016-03-08T13:19:53","modified_gmt":"2016-03-08T21:19:53","slug":"provisioning-services-bdm-creation-limitations","status":"publish","type":"post","link":"https:\/\/avtempwp.azurewebsites.net\/2016\/03\/provisioning-services-bdm-creation-limitations\/","title":{"rendered":"Provisioning Services BDM Creation Limitations"},"content":{"rendered":"<p>There are definitely pros and cons to using the various PVS boot options.\u00a0 If you aren\u2019t familiar or need a refresher, here they are:<\/p>\n<ol>\n<li>TFTP (with DHCP or PXE options)<\/li>\n<li>Create a Boot Device (BDM) using the included utility<\/li>\n<li>Let PVS XenDesktop Setup Wizard create a BDM partition\/drive<\/li>\n<\/ol>\n<p>For the purposes of this post, I will be talking about BDM.\u00a0 I\u2019m going to differentiate option #2 with option #3 by referring to #2 as \u201cBDM-TSB\u201d and #3 as \u201cBDM monolithic\u201d.<\/p>\n<p>The <a href=\"http:\/\/support.citrix.com\/content\/dam\/supportWS\/kA460000000CcClCAK\/Provisioning_Services_Boot_Process.pdf\">PVS Boot Process diagram<\/a> outlines the process I great detail, and I highly suggest you read it.\u00a0 All options are limited to 4 potential \u201cLogin servers\u201d.\u00a0 When using DNS, DNS based subnet affinity\u00a0 Here are some pro\u2019s and cons of each option<\/p>\n<h2>TFTP (w\/ PXE or DHCP)<\/h2>\n<ul>\n<li>Relies on external load balancing (potential off-host communication)<\/li>\n<li>Relies on TFTP service or third party TFPT server UDP port 69<\/li>\n<li>Prone to outages<\/li>\n<li>Built-in TFTP control panel configuration does not work on 2012 R2.\u00a0 Multi-nic binding scenarios could be difficult<\/li>\n<li>Third-party TFTP servers often without support<\/li>\n<li>Multi-threaded TFTP servers traditionally don\u2019t scale well<\/li>\n<li>Relies on either PXE or DHCP options for boot sever name<\/li>\n<\/ul>\n<h2>BDM-TSB<\/h2>\n<ul>\n<li>Highly customizable<\/li>\n<li>DNS or Static IP Definitions<\/li>\n<li>Relies on Two-stage boot service (and proprietary protocol on port UDP 6969)<\/li>\n<li>Can \u201cburn\u201d ISO or partitions<\/li>\n<li>BDM Utility does not identify which SCSI ID or other unique identifier for disks. Prone to misconfiguration (BE CAREFUL! CAN OVERWRITE YOUR MBR!)<\/li>\n<\/ul>\n<h2>BDM-Monolithic<\/h2>\n<ul>\n<li>Cannot customize<\/li>\n<li>Relies on \u201cCONFIGURE BOOTSTRAP\u201d settings for farm (more on this in a moment)<\/li>\n<li>Cannot use DNS<\/li>\n<li>Includes all components required for boot (No TFTP, load balancing, TSB needed)<\/li>\n<li>High degree of \u201cFault isolation\u201d<\/li>\n<li>Can be cumbersome to replace\/update<\/li>\n<li>Only available via XenDesktop setup wizard<\/li>\n<li>Newer (first release in 2013), not as widely used<\/li>\n<\/ul>\n<p>In selecting the BDM-Monolithic option, I was hoping to be able to design a highly fault tolerant environment that does not rely on the network stack (TFTP load balancing) or rely on the two stage boot service on each PVS server.\u00a0 However at scale, we ran into some issues.\u00a0 The design calls for 2 servers per subnet, in a single farm.\u00a0 Since it is <a href=\"http:\/\/discussions.citrix.com\/topic\/368082-xendesktop-setup-wizard-and-bdm\/\">currently not possible<\/a> to use DNS currently for the monolithic BDM and if there is a desire to <strong><em>not<\/em><\/strong> rely on DNS anyway\u00a0(say, if another group in the organization owns it), my next thought was to configure bootstrap differently per-server then connect the PVS console to each server, hoping it would use it\u2019s own BOOTSTRAP settings.\u00a0 Unfortunately, this seems to not be the case and it seems to select from the \u201ctop\u201d PVS server in the farm (in my case, this was the second one added to the farm), as shown below.<\/p>\n<p><a href=\"http:\/\/www.atumvirt.com\/wp-content\/uploads\/2016\/03\/image.png\"><img loading=\"lazy\" style=\"display: inline; background-image: none;\" title=\"image\" src=\"http:\/\/www.atumvirt.com\/wp-content\/uploads\/2016\/03\/image_thumb.png\" alt=\"image\" width=\"521\" height=\"280\" border=\"0\" \/><\/a>\u00a0<a href=\"http:\/\/www.atumvirt.com\/wp-content\/uploads\/2016\/03\/image-1.png\"><img loading=\"lazy\" style=\"display: inline; background-image: none;\" title=\"image\" src=\"http:\/\/www.atumvirt.com\/wp-content\/uploads\/2016\/03\/image_thumb-1.png\" alt=\"image\" width=\"522\" height=\"272\" border=\"0\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p>Based on this, I started digging.\u00a0 What else could we do to make this a bit easier, without having to reconfigure BOOTSTRAP for the whole farm every time we spin up a subnet?\u00a0 I turned to DotPeek and saw something interesting.<\/p>\n<p><a href=\"http:\/\/www.atumvirt.com\/wp-content\/uploads\/2016\/03\/image-2.png\"><img loading=\"lazy\" style=\"display: inline; background-image: none;\" title=\"image\" src=\"http:\/\/www.atumvirt.com\/wp-content\/uploads\/2016\/03\/image_thumb-2.png\" alt=\"image\" width=\"870\" height=\"163\" border=\"0\" \/><\/a><\/p>\n<p>If Login servers count = 0, we should hit that \u201celse\u201d statement and use DNS \u2013 which, we can\u2019t modify the hostname, but I\u2019ve confirmed is \u201cImageServer1\u201d (the default) if you look in the BDM that gets \u201cburned\u201d.<\/p>\n<p><a href=\"http:\/\/www.atumvirt.com\/wp-content\/uploads\/2016\/03\/image-3.png\"><img loading=\"lazy\" style=\"display: inline; background-image: none;\" title=\"image\" src=\"http:\/\/www.atumvirt.com\/wp-content\/uploads\/2016\/03\/image_thumb-3.png\" alt=\"image\" width=\"813\" height=\"162\" border=\"0\" \/><\/a><\/p>\n<p>However, once configured, you\u2019ll be hard pressed to remove servers!<\/p>\n<p><a href=\"http:\/\/www.atumvirt.com\/wp-content\/uploads\/2016\/03\/image-4.png\"><img loading=\"lazy\" style=\"display: inline; background-image: none;\" title=\"image\" src=\"http:\/\/www.atumvirt.com\/wp-content\/uploads\/2016\/03\/image_thumb-4.png\" alt=\"image\" width=\"393\" height=\"315\" border=\"0\" \/><\/a><\/p>\n<p>So while that is interesting, it would still be far more helpful that we simply use the BDM utility.<\/p>\n<p><a href=\"http:\/\/www.atumvirt.com\/wp-content\/uploads\/2016\/03\/image-5.png\"><img loading=\"lazy\" style=\"display: inline; background-image: none;\" title=\"image\" src=\"http:\/\/www.atumvirt.com\/wp-content\/uploads\/2016\/03\/image_thumb-5.png\" alt=\"image\" width=\"370\" height=\"405\" border=\"0\" \/><\/a><\/p>\n<p>It seems that the simplest solution would be for Citrix to simply allow the BDM-monolithic to be created by the Boot Device Manager configuration utility \u2013 something that is long overdue given the age of the PVS 7.x code base.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>There are definitely pros and cons to using the various PVS boot options.\u00a0 If you aren\u2019t familiar or need a refresher, here they are: TFTP (with DHCP or PXE options) Create a Boot Device (BDM) using the included utility Let PVS XenDesktop Setup Wizard create a BDM partition\/drive For the purposes of this post, I [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[10,43],"tags":[106],"_links":{"self":[{"href":"https:\/\/avtempwp.azurewebsites.net\/wp-json\/wp\/v2\/posts\/4361"}],"collection":[{"href":"https:\/\/avtempwp.azurewebsites.net\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/avtempwp.azurewebsites.net\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/avtempwp.azurewebsites.net\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/avtempwp.azurewebsites.net\/wp-json\/wp\/v2\/comments?post=4361"}],"version-history":[{"count":0,"href":"https:\/\/avtempwp.azurewebsites.net\/wp-json\/wp\/v2\/posts\/4361\/revisions"}],"wp:attachment":[{"href":"https:\/\/avtempwp.azurewebsites.net\/wp-json\/wp\/v2\/media?parent=4361"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/avtempwp.azurewebsites.net\/wp-json\/wp\/v2\/categories?post=4361"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/avtempwp.azurewebsites.net\/wp-json\/wp\/v2\/tags?post=4361"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}