Provisioning Services High Availability Considerations – Part 4

In the previous Provisioning Services High Availability Considerations blog, I spoke about placing your vDisks on a Network Attached Storage (NAS). Now I will talk about placing your vDisks on a Storage Area Network (SAN).

Placing your vDisks on a Storage Area Network (SAN) – iSCSI

Using a SAN to store the vDisks and access it by means of the iSCSI protocol provides a reliable way with good performance at a moderate cost to purchase, implement and maintain. This solution will provide highest levels of reliability.

What should we consider with this solution?

  • Requires software to manage the storage array.
  • iSCSI Initiator and MultiPath software must be installed and configured on each PVS; iSCSI Target software must be installed and configured on the File Server(s).
  • A Cluster or Parallel File System is required to ensure the integrity of the partition/LUN containing the vDisks.
  • I/O for vDisk input (loading from the share) and vDisk output (delivering to the Targed Devices) is handled by the same network link.

What are the recommendations?

  • NIC – teaming should be used to increase the reliability and the I/O between the Provisioning Servers, File Server and Target Devices.

Dedicated NIC – teams should be used for loading the vDisks and for delivering the vDisks to the Target Devices.








Placing your vDisks on a Storage Area Network (SAN) – Fibre Channel

Using a SAN to store the vDisks and access it by means of Fibre Channel provides a very reliable way with the highest levels of performance and reliability at highest cost. This solution will provide high degree of scalability to support increasing number of Target Devices.

What should we consider with this solution?

  • Additional Hardware (HBAs) required for every Provisioning Server.
  • Requires software to manage the storage array.
  • A Cluster or Parallel File System is required to ensure the integrity of the partition/LUN containing the vDisks.

What are the recommendations?  NIC – teaming should be used to increase the reliability and to I/O between the PVS Servers and the Target Devices.



As you can see, the SAN solutions are the ones providing highest reliability and scalability, but are the most expensive ones.





Normally using a SAN for vDisk storage with Provisioning Services requires that a shared file system be placed in front of the SAN to coordinate multiple server access to the NTFS formatted LUN(s).  Using Provisioning Services 5.1 you can use a SAN without a shared file system in some instances (you can have “read-only” vDisk storage). The desired boot modes for PVS target devices are important when using this feature since Provisioning Services only allows read-only shared access to the SAN LUN(s). Let’s see what are the main considerations when using this new feature:

  • You need to install Microsoft iSCSI initiator on all PVS servers that access the SAN.
  • It is only for Standard Image mode, Private Image mode is not supported.
  • If cache is located on server disk, a separate shared storage location that has read-write access is needed for write cache files.

I encourage you to attend this TechTalk session called:  “Simplifying Implementation of Provisioning Services

Hope to see you there on Thursday, August 27, 2009 at 1:00PM eastern time.

Elisabeth Teixeira – Principal Engineer – Worldwide Technical Readiness
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