CTERA has published The Cold Data Storage Report, an analysis of 16 petabytes of live production data across 856 file-share discovery scans in enterprise NAS environments, including regulated industries, and the headline number is that just 4.4% of stored capacity is actively used, which the report page defines as modified within a 90-day window. The rest is cold: 83.1% of total capacity sits in files that haven’t been modified in more than a year, 97.5% of individual files haven’t been modified in that time, 88% haven’t been accessed in more than a year, and only 9.9% of stored data was touched in any given 90-day window. CTERA’s framing is that enterprises are running their most expensive storage tier as a de facto archive, and that the bill for it shows up three places: cost, security exposure, and the quality of what AI systems retrieve.
Primary Storage as an Accidental Archive
None of this is a new problem; IT has had the ROT acronym (redundant, obsolete, or trivial) for years. What the report puts numbers on is the multiplier. Cold files on a primary array consume flash or hybrid capacity and then ride along through every backup pass, snapshot, and replication job that protects the tier, so the resources needed to maintain the estate scale with data nobody is reading. “When only 4.4% of capacity is actively used, enterprises are running their most expensive storage tier as what is effectively a cold archive. That creates a multiplier effect across storage and data protection costs, security exposure, and now the quality of information available to AI systems,” said Aron Brand, CTO of CTERA. His prescription is placement: “The answer isn’t simply to delete old data; it’s to make better decisions about where that data belongs. Information can be retained and protected without living on expensive primary storage.” That’s the same demand signal behind the archive-tier growth we saw in LTO shipments this year.
Security Exposure and AI Retrieval Quality
Inactive data typically stays in the same network-accessible shares, under the same access rights, as the data people use every day, so users and applications can reach far more information than daily operations require. Moving that data off the live tier shrinks the amount of sensitive material exposed in file systems without changing what’s retained.
The AI-readiness point is newer. As organizations point retrieval and search tools at their file estates, large volumes of historical or superseded material compete with current documents for relevance, and a model is only as reliable as what it retrieves. CTERA has been building toward this for a while; its n8n integration exposes file data to AI workflows, and its Fusion Direct targets files and objects for AI pipelines, and the report reads as the case for cleaning up the corpus before those pipelines index it. The full report is available from CTERA behind a registration form.
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