Just because we call all the data users aren't changing on a daily basis archival, that doesn't mean it's all the same. Depending on its source and usage patterns, different types of archival data can be best served by different storage techniques and media.
The most common type of archival data is made up of email
messages and files that have been put into the archive and may need to be accessed
by users transparently. Realizing
that object access rates fall off dramatically as objects age, system administrators
set up policies to migrate objects over 30 or 60 days old to an archival storage
system and replace them with some sort of pointer or stub so the user can still
access the data from its current location in their mailbox or home directory. Organizations with strict regulatory requirements
like SEC 17a-4 require that some data be retained, and will archive objects as they're
created and/or published/finalized and then replace the original files with
stubs as they reach the 30-60 day age.