{"id":4360,"date":"2012-08-24T15:41:27","date_gmt":"2012-08-24T13:41:27","guid":{"rendered":"https:\/\/ingmarverheij.com\/?p=4360"},"modified":"2013-11-30T12:49:29","modified_gmt":"2013-11-30T11:49:29","slug":"who-needs-pxe-for-citrix-provisioning-services","status":"publish","type":"post","link":"https:\/\/ingmarverheij.com\/en\/who-needs-pxe-for-citrix-provisioning-services\/","title":{"rendered":"Who needs PXE for Citrix Provisioning Services?"},"content":{"rendered":"

With Citrix Provisioning Services (PVS) the content of a disk can be streamed to a (virtual \/ physical) machine via the network. A (virtual) machine that boots needs a bootstrap to locate a PVS server (that has a vDisk available) and the ability to stream the disk to the machine.<\/p>\n

The bootstrap, the Boot Device Manager (BDM), needs to be delivered to the machine. It is common to deliver the BDM bootstrap via a Pre Execution Environment (PXE) network boot, but it\u2019s not required. Although the PXE method seems the most straight forward method (and most advocated), it it\u00a0 difficult to make it resilient.<\/p>\n

<\/p>\n

The PXE method<\/h1>\n

\"PXE<\/a>The Pre Execution Environment (PXE) method depends on a DHCP request, a PXE and a Trivial File Transfer Protocol (TFTP) server. After the machine sends a DHCP request it receives a DHCP response that contains the PXE server to contact. The PXE server streams the Boot Device Manager (BDM) to the machine via TFTP. After the machine has loaded the Boot Device Manager (BDM) the actual streaming of the vDisk via PVS starts.<\/p>\n

\"vDisk<\/a>Image from Citrix eDocs<\/em><\/p>\n

Achieving resilience, making the PXE and TFTP server high available, is a rather complex task and requires additional components like a NetScaler (or other load balancer) and (optionally) a third party TFTP server (to prevent streaming the vDisk through the NetScaler) and as a result two additional virtual machines per site. As described in Load Balancing TFTP \u2013 Anything But Trivial<\/a><\/p>\n

<\/h1>\n

Deliver directly<\/h1>\n

It is possible to deliver the Boot Device Manager (BDM) bootstrap directly to the machine, without using PXE and TFTP.<\/p>\n

\"Boot<\/a>\"Provisioning<\/a>With the \u2018Provisioning Services Boot Device Manager\u2019 tool you can easily create an ISO image (of 300K) which you can mount to your virtual machines. Especially in a virtual environment it is very easy to mount a ISO to a virtual machine. By mounting the ISO in the virtual machine template used in XenDesktop the correct boot image is always used. Alternatively the BDM bootstrap can be burned on a CD that you\u2019ll leave in a physical machine or store the bootstrap on the physical disk.<\/p>\n

It is even possible for OEMs to embed the bootstrap file on the target device, but I haven\u2019t seen a device that has it embedded yet.<\/em>\"vDisk<\/a><\/p>\n

Image from Citrix eDocs<\/em><\/p>\n

The best thing is that if there is an unforeseen circumstance and the machine is unable to boot, it can failover to the next boot device. This means you can use PXE as a failover method, where resiliency is less required. But to be honest, I don\u2019t think you should have to solutions in place \u2018just in case something goes wrong\u2019. Built it right and keep it right \"Knipogende
<\/p>\n

 <\/p>\n

What are the benefits?<\/h4>\n

There are mainly two big benefits;<\/p>\n

    \n
  1. The environment can be build with resiliency (or high available) with common off-the-shelf (COTS) products<\/li>\n
  2. The complexity is reduced\n