wissel.net

Usability - Productivity - Business - The web - Singapore & Twins

Long Term Storage and Retention


Not just since Einstein time is relative. For a human brain anything above 3 seconds is long term. In IT this is a little more complex.

Once a work artefact is completed, it runs through a legal vetting and it either goes to medium or long term storage. I'll explain the difference in a second. This logical flow manifests itself in multiple ways in concrete implementations: Journaling (both eMail and databases), archival, backups, write-once copies. Quite often all artifacts go to medium term storage anyway and only make it into long term storage when the legal criteria are met. Criteria can be:
  • Corporate & Trade law (e.g. the typical period in Singapore is 5 years)
  • International law
  • Criminal law
  • Contractual obligations (E.g. in the airline industry all plane related artefacts need to be kept at least until the last of that plane family has retired. E.g. the Boing 747 family is in service for more than 40 years)
For a successful retention strategy three challenges need to be overcome:
  1. Data Extraction

    When your production system doesn't provide retention capabilities, how to get the data out? In Domino that's not an issue, since it does provide robust storage for 25 years (you still need to BACKUP data). However if you want a cross application solution, have a look at IBM's Content Collector family of products (Of course other vendor's have solutions too, but I'm not on their payroll)
  2. Findability

    Now an artifact is in the archive, how to find it? Both navigation and search need to be provided. Here a clever use of Meta data (who, what, when, where) makes the difference between a useful system and a Bit graveyard. Meta data isn't an abstract concept, but the ISO 16684-1:2012 standard. And - YES - it uses the Dublin core, not to confuse with Dublin's ale
  3. Consumability / Resillience

    Once you found an artifact, can you open and inspect it. This very much boils down to: do you have software that can read and render this file format?
The last item (and the second to some extend) make the difference between mid-term and long-term storage. In a mid-term storage system you presume that, short of potential version upgrades, your software landscape doesn't change and the original software is still actively available when a need for retrieval arises. Furthermore you expect your retention system to stay the same.
On the other hand, in a long-term storage scenario you can't rely on a specific software for either search or artifact rendering. So you need to plan a little more carefully. Most binary formats fall short of that challenge. Furthermore your artefacts must be able to "carry" their meta data, so a search application can rebuild an access index when needed. That is one of the reasons why airline maintenance manuals are stored in DITA rather than an office format (note: docx is not compliant to ISO/IEC 29500 Strict).
The problem domain is known as Digital Preservation and has a reference implementation and congressional attention.
In a nutshell: keep your data as XML, PDF/A or TIFF. MIME could work too, it is good with meta data after all and it is native to eMail. The MIME-Trap to avoid are MIME-parts that are propriety binary (e.g. your attached office document). So proceed with caution
Neither PST, OST nor NSF are long term storage suitable (you still can use the NSF as the search database)
To be fully sure a long term storage would retain the original format (if required) as well as a vendor independent format.

Domino applications

IBM Notes is celebrating its 25th anniversary this year, having survived most of the contemporary packages at its inception (Wordstar, dBase, Harvard Graphics anyone?). So it looks like a save bet for long term storage. However without a Domino server or a Notes client (remember: usable without a specific vendor's software) it wouldn't be usable.
A solution that works:
Save each Notes document into a write-once file system (hold on for the format in a second) that includes all the meta data, so you can rebuild the Notes document from disk. ISO 16684-1:2012 covers Meta Data in XMP format, an Adobe contributed XML Schema. Read those specs!
Let's look at the simplified case, where your Notes document only contains fields other than RichText:
  1. Generate a PDF document. The document should have a layout that makes it easy to consume when opened in a PDF reader. So you can't just "print" the Notes form, you need to take care of sections, tabbed tables, popups etc. It's a little work, but there are nice tools available, in case you are not happy with just the editor
  2. Determine the storage location in your write once file system, where the PDF will reside. Add that to a Notes item in the current document
  3. Extract your Notes document as DXL or name/value pair list
  4. Push that meta data into the PDF. This is easier than it sounds, in PDFBox it is just a few lines of code:
    InputStream newXMPData = StringBufferInputStream("<myData><item name=\"PartNumber\">1234</item><item name=\"Color\">Red</color><myData>") ;
    PDMetadata newMetadata = new PDMetadata(pdfDoc, newXMLData, false );
    catalog.setMetadata( newMetadata );
    
  5. Finally save it to your write once file system
It gets a little more complicated with RichText and attachments, but that's another story for another time.

Update (Sep 15): Data format and integrity, is on other experts radar too!

Posted by on 14 August 2014 | Comments (1) | categories: IBM Notes Software

Comments

  1. posted by Nathan T. Freeman on Thursday 14 August 2014 AD:
    iso.org is a paywall for standards documentation?! Is that a joke?