Month: February 2009

Cost-effective Business Continuity Solutions – So much more than Data Back-up

Most Radiology PACS currently in use have some sort of data back-up in place. At the very least, the Directory database and the Data database are backed up daily to digital tape. In my opinion, digital tape is not reliable and the problem is you don’t know what data you have lost until you try and retrieve it. My low opinion of digital tape is supported by a number of reports from the field. I suspect the vendors that continue to insert digital tape back-up solutions in their early round quotes, do so in order to keep the price of the system down, but a much better solution is worth a few dollars more.

The “tape-less” back-up is a much better back-up solution. Instead of digital tape on a shelf or in a mechanical jukebox, a far more reliable and performance-oriented solution is to store the back-up copy of the Directory and the Data on spinning disk. Thanks to today’s pricing, a multi-processor, multi-core server coupled with a disk-based storage solution is only slightly more expensive than a digital tape library. I think the reliability is worth the additional investment.

Why stop there?

Instead of just writing a copy of the Directory on the back-up storage solution, why not install a second instance of the Directory application (Oracle, Sybase, DB2, SQL, etc.) on the back-up server? Now you have a reasonably cost-effective Disaster Recovery solution, depending on where you have physically placed that back-up system.

Why stop there?

Why not add a second instance of the PACS application to the back-up server? Now you have a reasonably cost-effective Business Continuity solution. Of course this complicates the PACS application considerably. The optimal software configuration would have the two Servers (Primary and Secondary) functioning in an “Active-Active”mode, and that would mean that the Directories are being automatically synchronized in near-real-time, and the study data is being copied from Primary to Secondary on a fairly regular basis.

Only the newest generation of PACS can support this configuration. Most of the PACS being sold today can support a “tape-less” back-up server, but they do not support a second instance of the Directory application on that back-up server. The few that do support a second Directory do not support a second instance of the PACS application. Fewer still that support a second instance of the Directory and the PACS application have the back-up system operating in a standby mode. The Back-up takes over only when the Primary is off-line for scheduled or unscheduled maintenance. While this version of back-up may not sound so bad, the fact is that the failover and eventual reconstitution processes are often manual and labor intensive.

The point in all of this is, with today’s cost of hardware it doesn’t make sense to settle for a back-up solution with questionable reliability, when a much more reliable Business Continuity solution is affordable. The problem is most PACS currently being sold are “old” generations of system architecture wrapped in pretty GUI and flashy 3D applications. While GUI and display applications are important, I believe that the system architecture that supports a solid Business Continuity solution is more important, and sooner or later those old generation PACS are going to be upgraded. You can tell a lot about the longevity of a PACS, by investigating the various back-up solutions that it can support. Why start a five year contract with an old PACS? Do you have room for a forklift in your data center?

Strategic Approach to PACS Storage Expansion

If your Radiology or Cardiology PACS is at least two years old, you’re probably running out of on-line storage capacity.  A more strategic approach to expanding the PACS on-line storage capacity is to deploy a completely separate storage solution, rather than simply adding more media to the storage solution that came with the PACS.  The right standalone Storage Subsystem could be the seed that grows into a PACS-Neutral Enterprise Archive.

In the two or more years since your existing PACS was installed, advances in CT and MR imaging have produced larger and larger data sets.  The addition of Full Field Digital Mammography has also added a large volume of digital image data to the PACS.  Echo and Cath Lab runs are also growing in data volume.  It is easy to understand how the amount of on-line storage  you originally projected for the PACS can no longer meet today’s actual storage requirements.

Up until a few years ago it was a common practice to configure a Radiology or Cardiology PACS with sufficient on-line storage media to manage the most recent 18 to 24 months of study data and install a Hierarchical Storage Management system to support near-line media in a jukebox, for example a digital tape library.  The near-line library has nearly unlimited expansion capabilities if it is linked to a shelf storage repository.  While this approach creates a sense of unlimited storage capacity, the practicality of the near-line library is limited by cartridge access rates and the manual loading and unloading of the tape cartridges.  All of this activity results in delays in image access.  After a few years of experience with the work flow associated with tape management, it is clear why the better solution is the expansion of the on-line storage solution.

Even if the Radiology PACS was configured with an all-spinning storage solution, the volume of storage required two or more years later has probably been underestimated. Whether the PACS is configured with a single or multiple tier storage solution, a storage upgrade is probably inevitable.  The question is, “What is the most strategic upgrade solution?”.

Adding additional media (drives), especially of the same type to the existing storage solution may not be the best solution.  In the last two or more years, the storage media technology has changed dramatically.  If the existing storage solution is approaching five years in age, it should probably be replaced, not expanded.   A completely new storage solution based on the latest technology would represent the best value, the most capacity per dollar invested.

Of course this type of upgrade, total replacement of the existing storage solution with a current generation storage solution with three to four times the capacity for the same dollars, will require a media to media data migration.   This type of data migration is not the onerous DICOM data migration that is required when one changes PACS, and that is the point!  A simple media to media migration moves all of the study data over to a new storage solution, preserving all of the ID errors, and retaining all of the DICOM idiosyncrasies of the existing PACS.  In my opinion, this could be viewed as a wasted opportunity.

The need for a storage expansion should be viewed as an opportunity to upgrade the storage technology AND normalize the image data format.

There are numerous arguments in favor of creating a PACS-Neutral Enterprise Archive: [1] Consolidation of multiple department PACS storage requirements into a single centrally administered storage solution, [2] Elimination of the cost of future DICOM data migrations, [3] Provision of data Acquisition and Management resources for imaging departments that have no PACS resources, and [4] Creation of a consolidated data repository for the Electronic Medical Record, accessible through the Physician Portal, viewable by a UniViewer display application.  The most significant problem limiting the deployment of this Enterprise Archive is the initial expense.

The same problem limited the early development of the Radiology PACS market.  Full-featured PACS was pretty expensive back in those days.  What finally got the PACS market going, what put the market on the upswing of the technology adoption curve was the invention of baby steps in the form of Teleradiology Systems and mini-PACS, individual systems that addressed individual needs that might be upgraded expanded or assimilated in to the larger more encompassing PACS that is commonplace today.

The emerging PACS-Neutral Enterprise Archive market needs a baby step, a “starter kit”, a “mini-PACS”.   I suggest that that starter kit could be a PACS-Neutral Storage Expansion subsystem for an existing PACS.  In  my next post, I’ll attempt to describe what I mean by a Neutral Storage Expansion subsystem, and why I believe that such a system is the right strategic move for any organization facing the need to expand their image storage.