Tiered storage: LTFS EE

A distributed file system on top of flash, disk and tape

GLUFS is the research project on integrating tapes formatted in accordance with the Linear Tape File System (LTFS) standard into the General Parallel File System (GPFS) as a tape storage tier for migration and backup.

Some of the GLUFS features are marketed by IBM as Linear Tape File System Enterprise Edition (LTFS EE) — a distributed file system on top of flash, disk, and tape.

GPFS is IBM’s disk cluster file system, which is extremely scalable. Seamlessly integrating LTFS tapes into GPFS makes tape look like disk, makes it easy to use, and creates a common namespace across disk and tape. Flexible migration policies allow administrators to optimize cost, access time, and power consumption by moving data between disk and tape.

When it comes to big data, tape is the most efficient storage medium whenever applications can live with the resulting access latency. GLUFS makes tape easy to use and scales disk clusters to truly big active archives at low cost.

Key features of the GLUFS approach are:

  • Global namespace: Common global namespace across disk and tape at GFPS level.
  • Simplified infrastructure and scalability: Metadata of migrated files is kept in GPFS so there is no need for external metadata servers. This allows the system to scale with the number of nodes, drives, and tapes.
  • Open format on portable media: Increased flexibility due to LTFS being an open standard.
  • Import/export and disaster recovery: Tapes can be exported from or imported into a GLUFS system. Tapes remain self-contained, including all meta-data from the original namespace. The global namespace can be recreated quickly from the meta-data on the tapes, i.e. the system becomes operational and the files become accessible without having to first move the data from the tapes.
  • Multi-node and multi-library support: Multiple GPFS nodes, multiple tape libraries, across multiple locations can be connected.
  • Flexibility: Cost/performance efficiency can be adjusted by disk/tape ratio and migration policies.
  • Simplified tape management: Makes tape management transparent to user by handling: cartridge pooling, reclamation, reconciliation, resource scheduling, replicas, fill policies etc.


GLUFS: Integration of disk and tape (GPFS and LTFS) within a distributed file system that provides a single name space and data lifecycle management (migration between disk and tape) functions.

Ask the expert

Mark A. Lantz

Mark A. Lantz

IBM Research scientist