What is the QDLS (Document Library Services)?

QDLS (Document Library Services) is an old, legacy file system within IBM i.
IBM states that QDLS dates back to System/36 and System/38 and is maintained only for backward compatibility.

Key characteristics of QDLS

  • Legacy, DOS‑style system
    QDLS uses 8.3 filenames, no mixed case, very limited special characters.
  • Slower and single‑threaded
    It cannot support multithreaded access. This creates problems with services like NetServer, which is multi‑threaded.
  • Used by older applications
    Some applications are hard‑coded to store files in QDLS and cannot easily be changed.
  • DLO‑based
    Stores Documents, Folders, etc., as Document Library Objects (DLOs)

QDLS vs. IFS — Side‑by‑Side Comparison

Feature
QDLS
IFS (root /QOpenSys / etc.)
Age
Legacy (System/36/38 era)
Modern IBM i architecture
Filename support
8.3 DOS‑style, no mixed case, limited characters
Long filenames, mixed case, special characters
Multithreading
Not supported; forced single‑thread access
Fully multithreaded
Typical purpose
Old apps, DLO objects, CPYTOPCD outputs
All modern file storage and application needs
Performance
Slow, blocking
Fast, scalable
IBM stance
Maintained for backward compatibility only; discouraged
Preferred and recommended

IBM has been recommending since 2010 that customers stop using QDLS

The IBM Power Ideas Portal contains an IBM‑related entry stating:

“IBM is recommending to stop using QDLS since 2010.”

This is the only directly surfaced statement in which IBM (or an IBM‑moderated channel) explicitly gives a date for when IBM began advising customers to stop using QDLS.

Important context

While IBM has never issued a formal End‑of‑Support (EOS) notice for QDLS, they have consistently described it as:

  • Obsolete legacy technology from System/36 & System/38
  • Maintained only for backward compatibility
  • Discouraged for modern workloads due to limitations and incompatibilities (e.g., naming, performance, multithreading issues)

Other IBM‑community sources—such as Service Express and technical blogs—strongly warn against using QDLS because of performance and multithreading conflicts, but these are advisories, not IBM-dated directives.

Is QDLS still supported?

Yes  QDLS (Document Library Services) remains supported as part of the IBM i operating system.

IBM’s own support documentation lists QDLS file‑system limits for currently supported OS versions V7R1, V7R2, and V7R3, which confirms that QDLS is still maintained and supported today.

Even though IBM considers QDLS an old, legacy file system dating back to System/36 and System/38, it is still included for backward compatibility

Has IBM ever announced an EOS (End of Support) for QDLS?

No. IBM has never published an end‑of‑support announcement specifically for QDLS.

What has reached EOS are older IBM i OS releases (such as V5R4 and V6R1), but QDLS continues to exist on all currently supported OS versions.

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