The healthcare industry’s ever-evolving technology and legislative front can make it challenging to stay current with the latest terminologies; however it is imperative that we maintain a solid understanding of current terms in order to make the most effective assessments and decisions. Laitek has assembled this glossary to facilitate your understanding of data migration and storage to help you identify the ideal course for your organization.

Direct PACS-Controlled Robotic Libraries – Some legacy PACS do not use Hierarchical Storage Managers (HSMs) for media management, instead controlling robotic libraries directly from the PACS server software. In some such cases, Laitek can still use the robotic library to read the stored media. Otherwise, Laitek provides hardware to read shelf media, and the assistance of customer personnel is required to load the media into Laitek reader devices.

Legacy Hierarchical Storage Managers (HSMs) –  For legacy PACS that use an HSM to manage the media, Laitek has automated scripts that invoke HSM functions to efficiently read data from storage volumes and transfer it to buffers in the migration server. Special care is taken with tape-based archives to read data in the order that it is written on the media, to avoid the severe performance impact and tape wear that results from random-access extraction of migration data. Migratek servers are configured with multi-terabyte disk buffers whenever near-line media are involved. HSMs also manage backup of archived data on duplicate or triplicate media. Laitek handles the retrieval from secondary storage, interacting with data center personnel as necessary, when recovery from backup media is required.

Near-line and offline media handling – Legacy PACS image data may be stored in online disk arrays (RAID / NAS / SAN), near-line sets of optical disks and tapes in robotic libraries, or offline shelf storage of tapes or disks. When any of the legacy data is in near-line or off-line storage, the data migration project contains an element of manual media handling.

Shelf media – Some legacy systems, particularly cardiovascular and interventional systems, rely on large collections of CD or DVD shelf media for their archived data. Laitek provides a robotic reader device that inputs batches of 50 or 100 disks assembled and loaded by customer personnel.

Validation – This step queries the destination PACS to determine that each study has the same number of images in the destination PACS as in the source PACS. This process sometimes requires special correction for anomalies such as duplication of images in the source PACS. Migratek validation is done for 100% of the studies in the source inventory. Any studies that fail to migrate are retried. The end result of validation is a report detailing any studies that cannot be migrated, and the reasons-read errors, corrupt data, illegal format–why it did not migrate. The number of “unmigratable” studies has in Laitek’s experience ranged from 0.02% to 2.0%.

Verification – This is a second quality check that confirms exact reconstruction of image data by Migratek Rapid Migration software. This is performed on a random sample of 500 studies or more, all of which are retrieved from the source and target systems by DICOM Query/Retrieve (C-MOVE) operations. For each image in every study, the copies retrieved from source and target systems are compared, and the test passes only if every pixel and every image attribute matches exactly. This comparison is performed using a Laitek-developed DICOM comparator program that is aware of alternate encodings of identical attributes.

Virtual Archive & Semperdata – The Migratek Migration Server also features Virtual Archive functionality that provides access to legacy data in post-go-live environments. The Virtual Archive is a DICOM Query/Retrieve Service Class Provider (SCP) that the new PACS uses to retrieve stat any needed studies that have not been migrated. The Virtual Archive retrieves the requested studies from the legacy archive or from migration buffers, as appropriate, transforms it as specified in the migration database, and delivers it to the new PACS.  The Virtual Archive provides important advantages over direct retrieval for the Legacy PACS:

• Specified data transformations of legacy data are applied, which would not occur in direct retrieval from the Legacy PACS.
• The migration server knows that the study has been migrated, avoiding collisions between migrated and direct-fetched studies.
• The virtual archive provides access to data in the migration exception repository.