What is Legacy Data?

Legacy data refers to any information an organization has stored from past systems, applications, or business processes that is still retained, often for regulatory, legal, or operational reasons. Even though the original environment it came from is outdated or no longer actively used. This data may live in old email archives, file servers, backup tapes, decommissioned applications, or disparate storage platforms. 

Why Does Legacy Data Still Exist? 

Legacy Data still exists due to several interconnected reasons, including long-term regulatory retention requirements that obligate organizations to preserve information for many years, pending or anticipated legal matters that require maintaining historical records, and slow or incomplete IT modernization efforts that leave older systems running far beyond their intended lifespan. 

 Many organizations also fear losing valuable business intelligence embedded in legacy records, which can make leaders reluctant to decommission older platforms. In addition, limited budgets, constrained technical resources, and competing organizational priorities often push data migration projects to the back burner. Together, these pressures create an environment where retiring outdated systems feels risky or impractical, ultimately resulting in the continued accumulation of information that is no longer actively used but remains critical for compliance, legal readiness, and operational continuity.

What Types of Data Are Commonly Considered Legacy Data? 

There's a vast majority of Data Types that are considered Legacy Data. Common examples include: 

Email and Messaging Platforms 

• Exchange on-premises (pre-Exchange 2010 environments) 
• Lotus Notes/Domino mail archives 
• Novell GroupWise archives 
• Early IM platforms like Lync/OCS or Skype for Business (retired) 

File and Content Repositories 

• On-premises Windows file servers are no longer maintained 
• Old network shares with unstructured data 
• SharePoint 2007/2010 on-premises farms 
• Legacy document management systems such as Documentum or FileNet (older versions) 

Archived or Decommissioned Applications 

• Retired CRM/ERP systems such as Siebel, SAP ECC, or JD Edwards legacy modules 
• Homegrown business applications developed in outdated frameworks 
• Industry-specific systems no longer supported by vendors (e.g., medical record systems, case management tools, financial platforms)

Backup and Storage Media 

• Tape archives stored in Iron Mountain or on-site vaults 
• Proprietary legacy storage arrays no longer supported 
• Offline disks or dormant cloud storage from deprecated platforms 
• Backup formats accessible only through retired software versions 

What Challenges Does Legacy Data Create? 

Legacy data often creates a wide range of operational and compliance issues that increasingly strain organizations as systems age. Outdated platforms introduce significant security risks because they lack modern protections, making them more vulnerable to cyberattacks. Maintaining these environments becomes costly over time due to high storage requirements and the ongoing expense of supporting infrastructure that is no longer efficient. 

 As legacy applications lose compatibility with modern systems, accessibility diminishes, forcing IT and end users to rely on workarounds or outdated tools. These complications also extend to eDiscovery, where legal teams face delays and inefficiencies when searching across multiple old systems that were never designed to integrate or scale with current needs. Finally, data integrity becomes a growing concern as older formats degrade or become unreadable, threatening the reliability and completeness of historical information essential for regulatory and legal obligations. 

How Does Legacy Data Affect eDiscovery? 

When legacy data affects eDiscovery, it becomes far more complex when relevant information resides in outdated or siloed systems. Challenges include: 

• Slow or incomplete searches across old platforms 
• Inability to apply modern search filtering or analytics 
• Difficulty preserving the chain of custody during extraction 
• Increased risk of missing key documents or communications 

Legal teams often struggle to meet deadlines or respond to litigation holds quickly when legacy data is involved. 

What Are the Risks of Ignoring Legacy Data? 

If organizations ignore the risks of legacy data, the following can occur: 

• Regulatory violations due to missing or inaccessible records 
• Increased costs for emergency recovery or restoration 
• Data breaches targeting outdated systems 
• Inconsistent retention policies leading to legal exposure 
• Operational inefficiencies from searching fragmented data sources 

How Can Organizations Modernize and Migrate Legacy Data? 

Successful legacy data modernization typically involves: 

1. Assessing what data exists, where it lives, who owns it, and how it is currently being used. This includes identifying redundant, obsolete, or trivial information, understanding dependencies between systems, and determining which data stores pose the highest compliance or security risks. 

2. Classifying data by regulatory, legal, and business requirements so organizations can determine what must be retained, what can be defensibly disposed of, and what needs to be migrated with priority. This step ensures alignment with industry regulations, internal policies, and litigation-readiness requirements. 

3. Migrating information to a modern platform such as Microsoft 365 or a cloud archive, ensuring that metadata, permissions, and retention settings are preserved. This often involves transforming outdated formats, resolving corruption issues, and validating data integrity during and after transfer. 

4. Automating workflows to ensure proper retention, lifecycle management, and defensible deletion going forward. Automation helps eliminate manual errors, enforces consistent policy application, and ensures compliance as the organization continues to generate new data. 

5. Decommissioning legacy systems safely once data is migrated, including validating that all necessary information has been captured, verifying that no legal holds remain, and ensuring that systems are securely retired to reduce cost, risk, and administrative overhead. 

What Benefits Come From Eliminating Legacy Systems? 

Organizations gain a lot of benefits from Eliminating Legacy systems, including: 

• Lower IT overhead and maintenance costs 
• Reduced organizational risk by eliminating outdated, unsupported systems 
• Stronger security posture 
• Enhanced compliance readiness through consistent policy enforcement 
• Consolidated data governance 
• Greater visibility into data assets through centralized management 
• Improved retention and defensible deletion practices aligned with governance frameworks 
• Faster, more accurate eDiscovery results 
• Improved user productivity and access to information 
• Increased agility for digital transformation 

Why Does Legacy Data Matter More Today Than Ever? 

In 2025, addressing legacy data has become critical as new global privacy laws, AI-driven compliance expectations, and increasingly sophisticated cyberattacks put pressure on organizations still relying on outdated systems. Legacy environments continue to present major risks, from security vulnerabilities to slowed eDiscovery workflows. Modern AI-powered tools like our very own AI Studio require clean, centralized, and accessible data to operate effectively. 

By modernizing legacy repositories, organizations can reduce risk, strengthen compliance, and unlock the full value of next-generation platforms such as Expireon, which delivers automated lifecycle management, defensible deletion, and efficient migration of historical data. 

Ready to take control of your legacy data? Explore how Expireon and AI Studio can transform your governance strategy and reduce risk today.