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Friday, November 13, 2009

TRAC: C1.7: Refreshing/migrating content

C1.7 Repository has defined processes for storage media and/or hardware change (e.g., refreshing, migration).

The repository should have triggers for initiating action and understanding of how long it will take for storage media migration, or refreshing — copying between media without reformatting the bitstream. Will it finish before the media is dead, for instance? Copying large quantities of data can take a long time and can affect other system performance. It is important that the process includes a check that the copying has happened correctly.

Repositories should also consider the obsolescence of any/all hardware components within the repository system as potential trigger events for migration. Increasingly, long-term, appropriate support for system hardware components is difficult to obtain, exposing repositories to risks and liabilities should they chose to continue to operate the hardware beyond the manufacturer or third-party support.

Evidence: Documentation of processes; policies related to hardware support, maintenance, and replacement; documentation of hardware manufacturers’ expected support life cycles.

ICPSR's archival storage consumes less than 6 TB of storage today. Over the past month we've made copies in other locations, and the time to copy it across a network is anywhere from a day to a week, depending upon the speed of the network. So that's much shorter than the lifespan of the media. :-)

The master copy resides on an EMC Celera NAS. From time to time one of the SATA drives that underpins archival storage will fail, and the Celera will fail over to its hot spare, and make a phone call for EMC to schedule a replacement. And, so in some odd way, the media gets refreshed on an incremental basis slowly over time.

We bought our Celera in 2005, and my expectation is that we'll likely replace it with something else in 2010; 2011 at the very latest. And so it's timely to start thinking about a written procedure for moving the master copy of the content from the Celera to the next storage platform. I don't think it will be a complicated procedure, and putting it together might make for a good future post.

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