Both terms are industry accepted terminology. So Tiers 1, 2 and 3 may refer to the performance of online storage or it may be used to refer to the locations of storage.
The site locations are; Primary
We can do disk to disk replication (media is mountable and data usable) These are both online We could also do disk to tape This is online and nearline
Secondary
We can use disk to disk replication This could still be online
We could do disk to tape In which case this could be offline
So we have different mechanisms we can use When we are trying to decide, firstly we need to look at; How valuable the information is What kind of information is it Where’s the best place to store it Typically we want to put it on the storage at the lowest cost that meets the requirement. We don’t want to keep all of our data on Tier 1 storage just because we have to keep something for 6 years because we are not allowed to delete it. It should be moved to lower cost storage that still meets the performance requirement.
The value of data will change over time. Backup is about recovering production data. The definition of archive is about storing infrequently used data for long periods of time, typically on lower cost media. There are often set periods that this data has to be kept.