The Unbreakable Enterprise Kernel Release 8 (UEK8) for Oracle Linux builds on Oracle’s enterprise-class Linux innovation. Compared to UEK7, UEK8 delivers substantial improvements in Btrfs, XFS, and NFS, with enhancements in performance, reliability, and usability—ideal for cloud-scale and mission-critical workloads.

Btrfs: Speed, Scale, and Simplification

Performance & Mount-Time Improvements

  • Compressed data now supports untransformed send/receive, improving snapshot replication efficiency.
  • Better support for writes larger than 64KB, which enables smoother large data operations.
  • A new tree block group structure significantly improves mount times on large file systems.
  • Enhanced block group logic reduces fragmentation and improves space reuse.

Quota Enhancements

  • Simple quota mode offers a lightweight alternative to traditional quota groups by linking extents directly to subvolumes.
  • Best suited for environments with immutable extents; shared data tracking is limited.

Operational Flexibility

  • Temporary FSIDs allow mounting cloned devices by generating a new UUID on mount.
  • New mount options include:
    • discard=async: (Default) Enables asynchronous discard/TRIM for SSDs.
    • ignoremetacsums: Ignores invalid metadata checksums.
    • ignoresuperflags: Ignores superblock conversion flags (useful for advanced recovery).

Concurrency and Device Management

  • Operations like send/receive, balance, shrink, and device removal are now parallelized.
  • Devices can be added while balance is paused, improving safety and flexibility.

Throughput Gains

  • Improved NOCOW write checks deliver up to 9% increase in write throughput.

XFS: Maturity Meets Modernization

Scalability and Format Flexibility

  • Block sizes larger than system page size are now supported.
  • Improved support for large files and virtual disk images with increased extent count limits.

Atomic File Updates

  • Atomic file content commits ensure consistency in write-heavy or failure-prone environments. UEK8 supports block atomic write. XFS atomic write is expected to be available in a future UEK8 update release.

Online fsck and Repair (Tech Preview)

  • Fully autonomous online file system check and repair is now available (Tech Preview).
  • Supports large, always-on environments requiring continuous uptime.

Creation Safeguards

  • mkfs.xfs now enforces a minimum file system size of 300MB to prevent performance and redundancy issues caused by undersized volumes.

NFS: Streamlined and Smarter Protocol Handling

NFSv4.2 READ_PLUS by Default

  • READ_PLUS enabled by default, enhancing sparse file handling and optimizing bandwidth for backup and analytics tools.

Protocol Cleanup

  • Deprecated and less-used NFS protocol features have been removed to modernize and streamline the stack.
  • See the UEK8 documentation for details on removed features.

Summary: Why These File System Enhancements Matter

UEK8 delivers practical, scalable file system improvements designed for Oracle environments.

 

Feature Area
Key Benefit in UEK8
Btrfs
Faster mounts, async discard, parallel operations
XFS
Atomic writes incoming update release, online repair, large extent support
NFS
Sparse file optimization with READ_PLUS
All FSs
Better support for large-scale, high-throughput workloads

 

Further reading